Etching method

ABSTRACT

An etching method in accordance with the present disclosure includes providing a substrate, which includes a silicon-containing film, in a chamber; and etching the silicon-containing film with a chemical species in plasma generated from a process gas supplied in the chamber. The process gas includes a phosphorus gas component and a fluorine gas component.

CROSS-REFERENCE TO RELATED APLICATIONS

The present application is a continuation of and claims priority toPCT/JP2020/041026, filed on Nov. 2, 2020, the entire disclosure of whichis incorporated herein by reference.

The present application is based upon and claims the benefit of theprior Japanese Patent Application No. 2019-203326, filed on Nov. 8,2019, PCT/JP2020/005847, filed on Feb. 14, 2020, and the prior JapanesePatent Application No. 2020-152786, filed on Sep. 11, 2020, the entiredisclosures of which are incorporated herein by reference.

TECHNICAL FIELD

Exemplary embodiments of the present disclosure relate to an etchingmethod, a process gas, and a plasma treatment system.

BACKGROUND

The production of electronic devices involves plasma etching ofsilicon-containing films on substrates. The plasma etching of thesilicon-containing film uses plasma generated from process gases.Conventionally, a process gas may contain a fluorocarbon gas, as aprocess gas for use in plasma etching of a silicon-containing film. Alsoconventionally, a process gas may contain a hydrocarbon gas and ahydrofluorocarbon gas, as a process gas for use in plasma etching of asilicon-containing film.

SUMMARY

In an exemplary implementation of the present disclosure, an etchingmethod includes providing a substrate, which includes asilicon-containing film, in a chamber; and etching thesilicon-containing film with a chemical species in plasma generated froma process gas supplied in the chamber, wherein the process gas includesa phosphorus gas component and a fluorine gas component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of an exemplary etching method according to thepresent disclosure.

FIG. 2 is a partially enlarged cross-sectional view of an exemplarysubstrate to which the method shown in FIG. 1 is applied.

FIG. 3 is a schematic view of a plasma treatment system according to thepresent disclosure.

FIG. 4A is a partially enlarged cross-sectional view of an exemplarysubstrate to which the method in FIG. 1 is applied.

FIG. 4B is a partially enlarged cross-sectional view of an exemplarysubstrate that is etched in plasma generated from a phosphorus-freeprocess gas.

FIG. 5 is an exemplary timing chart according to the present disclosure.

FIGS. 6A and 6B illustrate results of X-ray Pphotoelectron Spectroscopy(XPS) analysis of a protective film PF formed in an experimental exampleinvolving etching of a silicon oxide film and a silicon nitride film,respectively, in Step STP of the etching method in FIG. 1.

FIG. 7 is another exemplary timing chart according to the presentdisclosure.

FIG. 8 is a graph illustrating a relation between the flow rate of PF₃gas in the process gas and the etching rate of the silicon oxide film ina first experiment.

FIG. 9 is a graph illustrating a relation between the flow rate of PF₃gas in the process gas and the maximum width of a recess formed in thesilicon oxide film in the first experiment.

FIG. 10 is a graph illustrating a relation between the flow rate of PF₃in the process gas and the etching selectivity in the first experiment.

FIG. 11 is a graph illustrating a relation between the flow rate of PF₃gas and each of the etching rate of the silicon-containing film, theetching rate of the mask, and the etching selectivity in a secondexperiment.

FIG. 12 is a flow chart of another etching method according to thepresent disclosure.

FIG. 13 is a partially enlarged cross-sectional view of an exemplarysubstrate to which the method shown in FIG. 12 is applied.

FIG. 14 is a partially enlarged cross-sectional view of an exemplarysubstrate to which the method shown in FIG. 12 is applied.

FIG. 15 is another exemplary timing chart according to the presentdisclosure.

FIG. 16 is a graph illustrating the result of a seventh experiment.

FIG. 17 is a graph illustrating the results of eighth to eleventhexperiments.

FIG. 18A is a graph illustrating the result of a twelfth experiment.

FIG. 18B is a graph illustrating the result of a thirteenth experiment.

FIG . 19 is a diagram of controller circuitry that performscomputer-based operations described herein.

DETAILED DESCRIPTION OF THE DRAWINGS

The present disclosure provides a technique that enhances the etchingrate in a plasma etching process of a silicon-containing film.

Various exemplary embodiments will now be described.

An exemplary embodiment provides an etching method. The method involvesa step (a) of providing a substrate in a chamber of a plasma treatmentsystem. The substrate includes a silicon-containing film. The methodfurther involves a step (b) of etching the silicon-containing film witha chemical species in plasma generated from a process gas in thechamber. The process gas includes a phosphorus gas component, a fluorinegas component, and a hydrogen gas component. The hydrogen gas componentcontains at least one component selected from the group consisting ofhydrogen fluoride, Hz, ammonia, and hydrocarbons.

According to an exemplary embodiment, the process gas may furtherinclude a halogen gas component containing a halogen component otherthan fluorine component.

Another exemplary embodiment provides an etching method. The methodinvolves a step (a) of providing a substrate in a chamber of a plasmatreatment system.

The substrate includes a silicon-containing film. The method furtherinvolves a step (b) of etching the silicon-containing film with achemical species in plasma generated from a process gas in the chamber.The process gas includes a phosphorus gas component, a fluorine gascomponent, a hydrofluorocarbon gas component, and a halogen gascomponent. The halogen gas component contains a halogen component otherthan fluorine component.

According to an exemplary embodiment, the fluorine gas component mayinclude at least one gas selected from the group consisting of afluorocarbon gas and a carbon-free fluorine gas component. Thecarbon-free fluorine gas component may be nitrogen trifluoride gas orsulfur hexafluoride gas.

According to an exemplary embodiment, the halogen gas component may beCl₂ gas and/or HBr gas.

According to an exemplary embodiment, the ratio of the flow rate of asecond gas to the flow rate of a first gas in the process gas may beabove 0 and 0.5 or less. The first gas is all the gases included in theprocess gas excluding a phosphorus gas component. The second gas is aphosphorus-containing gas. The ratio may be 0.075 or more and 0.3 orless.

According to an exemplary embodiment, the method may further involve astep of forming a protective film on the side wall of a recess formed inthe step of etching. The protective film contains phosphorus-oxygenbonds contained in the process gas.

According to an exemplary embodiment, the step (b) involves periodicallyapplying pulsed bias electric power to a bottom electrode of a substratesupport that supports the substrate, when the plasma is present in thechamber. The bias electric power is radio-frequency bias power or pulsedDC voltage with negative polarity. The frequency defining the period inwhich pulsed bias electric power is applied to the bottom electrode maybe 5 Hz or more and 100 kHz or less.

According to an exemplary embodiment, the method may further involve astep of setting the temperature of the substrate support to 0° C. orless before the step (b).

Yet another exemplary embodiment provides an etching method. The methodincludes a step of providing a substrate in a chamber of a plasmatreatment system. The substrate includes a silicon-containing film and amask. The method includes a step of generating plasma from a process gasin the chamber to etch the silicon-containing film.

The process gas includes a hydrogen fluoride gas component, a phosphorusgas component, and a carbon gas component.

According to an exemplary embodiment, among the flow rate of thehydrogen fluoride gas component, the flow rate of the phosphorus gascomponent, and the flow rate of the carbon gas component, the flow rateof the hydrogen fluoride gas component may be largest.

According to an exemplary embodiment, the process gas may furtherinclude a rare gas. Among the flow rates of all gases in the process gasexcluding the rare gas, the flow rate of the hydrogen fluoride gascomponent may be largest.

According to an exemplary embodiment, in the step (b), the temperatureof a substrate support that supports the substrate may be set to atemperature of 0° C. or less or a temperature of −40° C. or less.

According to an exemplary embodiment, the phosphorous-containing gas maycontain a halogen component. The halogen component in the phosphorousgas component may be a halogen component other than fluorine component.

According to an exemplary embodiment, the proportion of the flow rate ofthe phosphorus gas component in the sum of the flow rate of the hydrogenfluoride gas component, the flow rate of the phosphorus gas component,and the flow rate of the carbon gas component may be 2% or more.

According to an exemplary embodiment, the process gas may furtherinclude a fluorine-free halogen gas component. The proportion of theflow rate of the halogen gas component in the sum of the flow rate ofthe hydrogen fluoride gas component, the flow rate of the phosphorus gascomponent, the flow rate of the carbon gas component, and the flow rateof the halogen gas component may be above 0% and 10% or less.

According to an exemplary embodiment, the silicon-containing film mayinclude a silicon oxide film. The silicon-containing film may furtherinclude a silicon nitride film.

Another exemplary embodiment provides a process gas for plasma etchingof a silicon oxide film. The process gas includes a hydrogen fluoridegas component, a phosphorus gas component, and a carbon gas component.

According to an exemplary embodiment, among the flow rate of thehydrogen fluoride gas component, the flow rate of the phosphorus gascomponent, and the flow rate of the carbon gas component, the flow rateof the hydrogen fluoride gas component may be largest.

According to an exemplary embodiment, the process gas may furtherinclude a rare gas. Among the flow rates of all the gases in the processgas excluding the rare gas, the flow rate of the hydrogen fluoride gascomponent may be largest.

According to an exemplary embodiment, the phosphorous gas component maycontain a halogen component. The halogen component may be a halogencomponent other than fluorine component.

According to an exemplary embodiment, the proportion of the flow rate ofthe phosphorus gas component in the sum of the flow rate of the hydrogenfluoride gas component, and the flow rate of the phosphorous gascomponent, and the flow rate of the carbon gas component may be 2% ormore.

Various exemplary embodiments will now be described in detail inreference to the accompanying drawings. In the drawings, the samereference numeral or symbol is assigned to the same or similarcomponents.

FIG. 1 is a flow chart of an exemplary etching method according to thepresent disclosure. The etching method (hereinafter, method MT) shown inFIG. 1 is applied to a substrate having a silicon-containing film. Themethod MT etches the silicon-containing film.

FIG. 2 is a partially enlarged cross-sectional view of an exemplarysubstrate to which the method shown in FIG. 1 can be applied. Asubstrate W shown in FIG. 2 can be used in production of devices, suchas DRAMs and 3D-NANDs. The substrate W has a silicon-containing film SF.The substrate W may further have an underlying region UR. Thesilicon-containing film SF may be disposed on the underlying region UR.

The silicon-containing film SF may be a silicon-containing dielectricfilm. The silicon-containing dielectric film may include a silicon oxidefilm or a silicon nitride film. The silicon-containing dielectric filmmay be of any other form that contains silicon. The silicon-containingfilm SF may be a silicon film (for example, a polycrystalline siliconfilm). The silicon-containing film SF may include at least one of asilicon nitride film, a polycrystalline silicon film, acarbon-containing silicon film, and a low-dielectric-constant film. Thecarbon-containing silicon film may include a SiC film and/or a SiOCfilm. The low-dielectric-constant film contains silicon and may be usedas an interlayer insulating film. The silicon-containing film SF mayinclude at least two silicon-containing sublayers having differentcompositions. The at least two silicon-containing sublayers may includea silicon oxide sublayer and a silicon nitride sublayer. Thesilicon-containing film SF may have a multilayer configuration includingalternately stacked one or more silicon oxide sublayers and one or moresilicon nitride sublayers. The silicon-containing film SF may have amultilayer configuration including alternately stacked silicon oxidesublayers and silicon nitride sublayers. Alternatively, the at least twosilicon-containing sublayers may include a silicon oxide sublayer and asilicon sublayer. The silicon-containing film SF may have a multilayerconfiguration including, for example, alternately stacked one or moresilicon oxide sublayers and one or more silicon sublayers. Thesilicon-containing film SF may have a multilayer configuration includingalternately stacked silicon oxide sublayers and polysilicon sublayers.Alternatively, the at least two silicon-containing films may include asilicon oxide sublayer, a silicon nitride sublayer, and a siliconsublayer.

The substrate W may further include a mask MK. The mask MK is disposedon the silicon-containing film SF. The mask MK is formed with a materialhaving an etching rate that is lower than that of the silicon-containingfilm SF in Step ST2. The mask MK may be formed with an organic material.In detail, the mask MK may contain carbon. The mask MK may be formedfrom, for example, an amorphous carbon film, a photoresist film, or aspin-on-carbon film (SOC film). Alternatively, the mask MK may be formedfrom a silicon-containing film, such as a silicon-containingantireflective film. Alternatively, the mask MK may be ametal-containing mask formed with a metal-containing material, such astitanium nitride, metal tungsten, or tungsten carbide. The mask MK mayhave a thickness of 3 μm or more.

The mask MK is patterned. In detail, the mask MK has a pattern to be 2 0transferred onto the silicon-containing film SF in Step ST2. After thepattern of the mask MK is transferred onto the silicon-containing filmSF, the silicon-containing film SF may have a structure such as a recessor trench (recess). The aspect ratio of the structure formed on thesilicon-containing film SF in Step ST2 may be 20 or more, 30 or more, 40or more, or 50 or more. The mask MK may have a line-and-space pattern.

In the method MT, a plasma treatment system is used for etching of thesilicon-containing film SF. FIG. 3 is a schematic diagram of the plasmatreatment system according to the present disclosure. A plasma treatmentsystem 1 shown in FIG. 3 includes a chamber 10 that has an internalspace 10s. The chamber 10 includes a chamber body 12 that has asubstantially cylindrical shape. The chamber body 12 is composed of, forexample, aluminum. The chamber body 12 has an inner wall having ananticorrosive film that may be composed of a ceramic substance, such asaluminum oxide or yttrium oxide.

The side wall of the chamber body 12 has a substrate lane 12 p. Thesubstrate W is delivered between the internal space lOs and the exteriorof the chamber 10 through the substrate lane 12 p. The substrate lane 12p is opened or closed by a gate valve 12 g. The gate valve 12 g isdisposed along a side wall of the chamber body 12. A support 13 isdisposed on the bottom face of the chamber body 12. The support 13 iscomposed of an insulating material. The support 13 has a substantiallycylindrical shape. The support 13 extends vertically from the bottomface of the chamber body 12 in the internal space 10 s. The support 13bears a substrate support 14. The substrate support 14 is configured tosupport the substrate W in the internal space 10 s.

The substrate support 14 includes a lower electrode 18 and anelectrostatic chuck 20. The substrate support 14 may further include anelectrode plate 16. The electrode plate 16 is composed of a conductorsuch as aluminum and has a substantially discoid shape. A bottomelectrode 18 is disposed on the electrode plate 16. The bottom electrode18 is composed of a conductor, such as aluminum, and has a substantiallydiscoid shape. The bottom electrode 18 is electrically connected to theelectrode plate 16.

The electrostatic chuck 20 is disposed on the lower electrode 18. Thesubstrate W is disposed on the electrostatic chuck 20. The electrostaticchuck 20 has a body and an electrode. The body of the electrostaticchuck 20 has a substantially discoid shape and is composed of adielectric material. The electrode in the electrostatic chuck 20 is afilm-like electrode disposed in the body of the electrostatic chuck 20.The electrode in the electrostatic chuck 20 is connected to a DC powersource 20 p via a switch 20 s. When a voltage from the DC power source20 p is applied to the electrode of the electrostatic chuck 20, anelectrostatic attractive force occurs between the electrostatic chuck 20and the substrate W. The electrostatic chuck 20 attracts the substrate Wby the electrostatic attractive force and holds the substrate W thereon.

An edge ring 25 is disposed on the substrate support 14. The edge ring25 may be composed of silicon, silicon carbide, or quartz. The substrateW is disposed on the electrostatic chuck 20 and is positioned in aregion surrounded by the edge ring 25.

The bottom electrode 18 has a flow channel 18 f therein. The flowchannel 18 f is supplied with a heat exchange medium (for example,refrigerant) through piping 22 a from a chiller disposed outside thechamber 10. The heat exchange medium supplied to the flow channel 18 freturns to the chiller through piping 22 b. In the plasma treatmentsystem 1, the temperature of the substrate W on the electrostatic chuck20 is controlled by heat exchange between the heat exchange medium andthe bottom electrode 18. The plasma treatment system 1 includes a gassupply line 24. The gas supply line 24 supplies a gap between the upperface of the electrostatic chuck 20 and the rear face of the substrate Wwith a heat-transfer gas (for example, He gas) from a heat-transfer gassupplying mechanism.

The plasma treatment system 1 further include an upper electrode 30. Theupper electrode 30 is disposed above the substrate support 14. The upperelectrode 30 is supported at the top portion of the chamber body 12 witha fixing member 32. The fixing member 32 is composed of an insulatingmaterial. The upper electrode 30 and the fixing member 32 close theupper recess of the chamber body 12.

The upper electrode 30 may include a top plate 34 and a support 36. Thelower surface of the top plate 34 faces the internal space 10 s anddefines the internal space 10 s. The top plate 34 may be composed of aconductor or semiconductor that has low resistance to generate lessjoule heat. The top plate 34 has gas outlet recesses 34 a extendingthrough the thickness.

The support 36 detachably supports the top plate 34. The support 36 iscomposed of a conductive material such as aluminum. The support 36 hasan internal gas diffusion space 36 a. The support 36 has gas recesses 36b extending downward from the gas diffusion space 36 a. These gasrecesses 36 b are in communication with the respective gas outlet 34 a.The support 36 has a gas inlet port 36 c. The gas inlet port 36 c isconnected to the gas diffusion space 36 a. The gas inlet port 36 c isalso connected to a gas feed pipe 38.

A group of gas sources 40 is connected to the gas feed pipe 38 through agroup of flow rate controllers 41 and a group of valves 42. The group offlow rate controllers 41 and the group of valves 42 make up a gas supplyunit. The gas supply unit may further include a group of gas sources 40.The group of gas sources 40 includes gas 3 0 sources. The gas sourcesinclude process gas sources used in the method MT. The group of flowrate controllers 41 includes flow rate controllers. Each of the flowrate controllers of the group of flow rate controllers 41 is a mass flowcontroller or a pressure control type flow controller. The group ofvalves 42 includes open-close valves. Each of the gas sources 40 isconnected to the gas feed pipe 38 through the corresponding flow ratecontroller 41 and the corresponding open-close valve 42. Controller 41includes, or is controlled by, processing circuitry which will describedbelow with respect to FIG. 19.

In the plasma treatment system 1, a detachable shield 46 is disposed onthe face of the inner wall of the chamber body 12 and the periphery ofthe support 13. The shield 46 can prevent deposition of reactionbyproducts in the chamber body 12. The shield 46 is formed, for example,by providing an anticorrosive film on the aluminum base. Theanticorrosive film may be composed of a ceramic material, such asyttrium oxide.

A baffle plate 48 is disposed between the support 13 and the side wallof the chamber body 12. The baffle plate 48 is composed of, for example,an aluminum material provided with an anticorrosive film (e.g., yttriumoxide film). The baffle plate 48 has multiple through holes. A gasoutlet port 12 e is provided below the baffle plate 48 at the bottom ofthe chamber body 12. The gas outlet port 12 e is connected to anevacuation system 50 through a gas outlet pipe 52. The evacuation system50 includes a pressure regulating valve and a vacuum pump such as aturbo-molecular pump.

The plasma treatment system 1 includes a radio-frequency power source 62and a bias power source 64. The radio-frequency power source 62generates radio-frequency power HF. The radio-frequency power HF has afirst frequency suitable for generation of plasma. The first frequencyranges, for example, from 27 MHz to 100 MHz. The radio-frequency powersource 62 is coupled to the bottom electrode 18 via a matching unit 66and the electrode plate 16. The matching unit 66 has a circuit formatching of the output impedance of the radio-frequency power source 62and the impedance at the load (at the bottom electrode 18) of theradio-frequency power source 62. It should be noted that theradio-frequency power source 62 may be coupled to the upper electrode 30via the matching unit 66. The radio-frequency power source 62 functionsas a part of an exemplary plasma generator.

The bias power source 64 generates bias electric power. The bias powersource 64 is electrically coupled to the bottom electrode 18. The biaselectric power has a second frequency that is lower than the firstfrequency. For example, the second frequency ranges from 400 kHz to13.56 MHz. In the case where bias electric power is used withradio-frequency power HF, the bias electric power is applied to thesubstrate support 14 (in an example, the bottom electrode 18) so thations are attracted to the substrate W. Upon application of the biaselectric power to the bottom electrode 18, the potential of thesubstrate W disposed on the substrate support 14 varies in response toeach period of the second frequency.

In one embodiment, the bias electric power may be radio-frequency powerLF having a second frequency. In the case where the radio-frequencypower LF is used with the radio-frequency power HF, the radio-frequencypower LF is used as radio-frequency bias power that allows the substrateW to attract ions. The bias power source 64, which generateradio-frequency power LF, is coupled to the bottom electrode 18 via amatching unit 68 and the electrode plate 16. The matching unit 68 has acircuit for matching of the output impedance of the bias power source 64and the impedance at the load (at the bottom electrode 18) of the biaspower source 64.

The plasma may be generated using only the radio-frequency power LFwithout use of the radio-frequency power HF, in other words, usingsingle radio-frequency power. In such a case, the radio-frequency powerLF may have a frequency higher than 13.56 MHz, for example, 40 MHz. Insuch a case, the plasma treatment system 1 may not require theradio-frequency power source 62 or the matching unit 66. In such a case,the bias power source 64 makes up an exemplary plasma generator.

In another embodiment, the bias electric power may be pulsed DC voltage.The pulsed DC voltage is periodically generated and applied to thebottom electrode 18. The period of the pulsed DC voltage is defined bythe second frequency. The period of the pulsed DC voltage includes twoterms. The DC voltage in at least one of the two terms is a DC voltagewith negative polarity. The level (or absolute value) of the DC voltageat one of the two terms is higher than the level (or absolute value) ofthe DC voltage at the other term. The DC voltage at the other term mayhave either negative polarity or positive polarity. The level of the DCvoltage with negative polarity at the other term may be higher than zeroor be zero. In this embodiment, the bias power source 64 is connected tothe bottom electrode 18 via a low-pass filter and the electrode plate16. The pulse waves used as bias electric power may include a pulsedvoltage having a waveform different from a direct-current waveform.

In one embodiment, the bias power source 64 may apply continuous wavesof the bias electric power to the bottom electrode 18. In detail, thebias power source 64 may continuously apply bias electric power to thebottom electrode 18. The continuous waves of the bias electric power maybe applied to the bottom electrode 18 during Step STP, i.e., Steps ST2and ST3 in the method MT.

In another embodiment, the bias power source 64 may apply pulsed biaselectric power to the bottom electrode 18. The pulsed bias electricpower may be periodically applied to the bottom electrode 18. The periodof the pulsed bias electric power is defined by a third frequency. Thethird frequency is lower than the second frequency. The third frequencyis, for example, 1 Hz or more and 200 kHz or less. In another example,the third frequency may be 5 Hz or more and 100 kHz or less.

The period of the pulsed waves of the bias electric power includes twoterms, i.e., a term H and a term L. The level of the bias electric power(or the level of pulses of the bias electric power) at the term H ishigher than the level of the bias electric power at the term L. Avariation in level of the bias electric power allows the pulsed biaselectric power to be applied to the bottom electrode 18. The level ofthe bias electric power at the term L may be higher than zero.Alternatively, the level of the bias electric power at the term L may bezero. In summary, supply of the pulsed bias electric power to be appliedto the bottom electrode 18 is alternately switched between continuationand cessation. If the bias electric power is radio-frequency power LF,the level of the bias electric power is the level of the radio-frequencypower LF. If the bias electric power is radio-frequency power LF, thelevel of the radio-frequency power LF in the pulsed bias electric powermay be 2 kW or more. If the bias electric power is pulsed DC voltagewith negative polarity, the effective level of the bias electric powercorresponds to the absolute DC voltage with a negative polarity. Theduty ratio of the pulsed bias electric power, in detail, the rate of theterm H to the period of the pulsed bias electric power is, for example,1% or more and 80% or less. In another example, the duty ratio of thepulsed bias electric power may be 5% or more and 50% or less.Alternatively, the duty ratio of the pulsed bias electric power may be50% or more and 99% or less. The pulsed bias electric power may beapplied to the bottom electrode 18 in Steps ST2 and ST3 in the methodMT.

In one embodiment, the radio-frequency power source 62 may supplycontinuous waves of the radio-frequency power HF. In other words, theradio-frequency power source 62 may continuously supply theradio-frequency power HF. The continuous waves of the radio-frequencypower HF can be supplied during Step STP, i.e., Steps ST2 and Step ST3in the method MT.

In another embodiment, the radio-frequency power source 62 may supplythe pulsed waves of the radio-frequency power HF. The pulsed waves ofthe radio-frequency power HF can be periodically supplied. The pulsedradio-frequency power HF is defined by a fourth frequency. The fourthfrequency is lower than the second frequency. In one embodiment, thefourth frequency equals the third frequency. The period of the pulsedwaves of the radio-frequency power HF includes two terms, a term H and aterm L. The level of the radio-frequency power HF at the term H ishigher than the level of the radio-frequency power HF at the term L ofthe two terms. The level of the radio-frequency power HF at the term Lmay be higher than zero or be zero.

The period of the pulsed radio-frequency power HF may be insynchronization with the period of the pulsed bias electric power. Indetail, the term H in the period of the pulsed radio-frequency power HFmay be in synchronization with the term H in the period of the pulsedbias electric power. Alternatively, the term H in the period of thepulsed radio-frequency power HF may not be in synchronization with theterm H in the period of the pulsed bias electric power. The length ofthe term H in the period of the pulsed radio-frequency power HF may bethe same as or different from the length of the term H in the period ofthe pulsed bias electric power.

At the start of the plasma treatment in the plasma treatment system 1,gas is supplied from the gas supply unit to the internal space 10 s. Theradio-frequency power HF and/or bias electric power is also supplied togenerate a radio-frequency electric field between the upper electrode 30and the bottom electrode 18. The radio-frequency electric fieldgenerates plasma from the gas in the internal space 10 s.

The plasma treatment system 1 further includes a controller 80. Thecontroller 80 may be a computer provided with, for example, a processor,a storage such as a memory, an input system, a display, and a signal I/Ointerface. The controller 80 controls individual components of theplasma treatment system 1. The controller 80 allows an operator to inputany command for controlling the plasma treatment system 1 through aninput device. The controller 80 allows a display to present theoperational state of the plasma treatment system 1 visually. The storagestores control programs and recipe data. The processor executes thecontrol programs to execute various processes with the plasma treatmentsystem 1, and controls individual components in the plasma treatmentsystem 1 in accordance with recipe data. A structural configuration ofcontroller 80 is described below with respect to FIG. 19.

Referring again to FIG. 1, the substrate W shown in FIG. 2 is treated inthe plasma treatment system 1 in accordance with the method MT. Themethod MT is carried out through control of individual components by thecontroller 80 in the plasma treatment system 1. The followingdescription also includes the control of individual components in theplasma treatment system 1 by the controller 80 in the method MT. Thefollowing description is carried out with reference to FIGS. 1, 4A, 4B,and 5. FIG. 4A is a partially enlarged cross-sectional view of anexemplary substrate to which the method shown in FIG. 1 is applied; andFIG. 4B is a partially enlarged cross-sectional view of an exemplarysubstrate that is etched in plasma generated from a phosphorus-freeprocess gas. FIG. 5 is an exemplary timing chart in the method accordingto an exemplary embodiment where the horizontal axis indicates timewhile the vertical axis indicates the level of the radio-frequency powerHF, the level of the bias electric power, and the supply of the processgas. The level “L” in the radio-frequency power HF indicates that noradio-frequency power HF is supplied or the level of the radio-frequencypower HF is lower than the level “H”. The level “L” in the bias 2 0electric power indicates that no bias electric power is applied to thebottom electrode 18 or the level of the bias electric power is lowerthan the level “H”. The symbol “ON” in the supply of the process gasindicates that the process gas is being supplied into the chamber 10whereas the symbol “OFF” indicates that the process gas is not beingsupplied into the chamber 10.

With reference to FIG. 1, the method MT starts with Step ST1. Thesubstrate W is disposed in the chamber 10 in Step ST1. The substrate Wis held on the electrostatic chuck 20 in the chamber 10. The substrate Wmay have a diameter of 300 mm.

Step STP is then performed in the method MT. Step STP involves a plasmatreatment of the substrate W. Plasma is generated from the process gasin the chamber 10 in Step STP. The method MT includes Step ST2. Step ST2is carried out in Step

STP. The method MT may further include Step ST3. Step ST3 may be carriedout in Step STP. Step ST2 and Step ST3 may be carried out at the sametime or independently.

In Step ST2, the silicon-containing film SF is etched by a chemicalspecies in plasma generated from the process gas in the chamber 10 inStep STP. In Step ST3, a protective film PF is formed on the substrate Wby the chemical species generated from the process gas in the chamber 10in Step STP. The protective film PF is formed on the side wall of arecess formed in the silicon-containing film SF.

The process gas used in Step STP contains a halogen gas component and aphosphorus gas component. The halogen gas component contained in theprocess gas may be a fluorine gas component. The process gas may containat least one halogen-containing molecule. The at least onehalogen-containing molecule in the process gas may be fluorocarbon orhydrofluorocarbon. Examples of the fluorocarbon include CF₄, C₃F₈, C₄F₆,and C₄F₈. Examples of the hydrofluorocarbon include CH₂F₂, CHF₃, andCH₃F. The hydrofluorocarbon may include two or more carbon atoms. Thehydrofluorocarbon may include, for example, three carbon atoms or fourcarbon atoms.

The process gas may contain at least one molecule containing thephosphorous component. The molecules containing the phosphorouscomponent may be phosphorus oxides, such as tetraphosphorus decaoxide(P₄O₁₀), tetraphosphorus octoxide (P₄O₈), and tetraphosphorus hexaoxide(P₄O₆). Tetraphosphorus decaoxide is also called diphosphorus pentoxide(P₂O₅). The molecules containing the phosphorous component may bephosphorus halides, such as phosphorus trifluoride (PF₃), phosphoruspentafluoride (PF₅), phosphorus trichloride (PCl₃), phosphoruspentachloride (PCl₅), phosphorous tribromide (PB_(r3)), phosphoruspentabromide (PB_(r5)), and phosphorus triiodide (PI₃). In other words,the molecules containing the phosphorous component may contain fluorinecomponent as a halogen component. Alternatively, the moleculescontaining the phosphorous component may contain a halogen componentother than fluorine component, as a halogen component. The moleculescontaining the phosphorous component may be phosphoryl halides, such asphosphoryl fluoride (POF₃), phosphorus oxychloride (POCl₃), andphosphoryl bromide (POB_(r3)). The molecules containing the phosphorouscomponent may be phosphine (PH₃), calcium phosphide (Ca₃P₂), phosphoricacid (H₃PO₄), sodium phosphate (Na₃PO₄), and hexafluorophosphoric acid(HPF₆). The molecules containing the phosphorous component may befluorophosphines (H_(x)PF_(y)), where the sum of x and y is three orfive. Examples of the fluorophosphines include HPF₂ and H₂PF3. The atleast one phosphorus component in the process gas may be at least one ofthese molecules containing the phosphorous component. For example, theprocess gas may contain at least one molecule containing the phosphorouscomponent selected from the group consisting of PF₃, PCl₃, PF₅, PCl₅,POCl₃, PH₃, PBr₃, and PBr₅. A solid or liquid molecule containing thephosphorous component may be heated to vaporization and then introducedin the chamber 10.

The process gas used in Step STP may further contain a carbon componentand a hydrogen component. Examples of the process gas include H₂,hydrogen fluoride (HF), hydrocarbons (C_(x)H_(y)), hydrofluorocarbons(CH_(x)F_(y)), and NH₃ as the molecule containing the hydrogencomponent, where x and y are each a natural number. These gases may beused alone or in combination. Examples of the hydrocarbon includes CH₄and C₃H₆. Examples of the carbon component in the process gas includefluorocarbons and hydrocarbons (for example, CH₄). The process gas mayfurther contain an oxygen component. For example, the process gas maycontain O₂. Alternatively, the process gas may be free of oxygen.

The process gas used in Step STP may contain a hydrogen fluoride gascomponent and a phosphorus gas component.

In one embodiment, the process gas includes a phosphorus gas component,a fluorine gas component, and a hydrogen gas component. The hydrogen gascomponent contains at least one component selected from the groupconsisting of hydrogen fluoride (HF), H₂, ammonia (NH₃), andhydrocarbons. The phosphorus gas component includes at least one of thephosphorous compounds listed above. The fluorine gas component includesat least one component selected from the group consisting of afluorocarbon gas and a carbon-free fluorine gas component. Thefluorocarbon gas component is a gas containing the fluorocarboncomponent listed above. The carbon-free fluorine gas component is, forexample, nitrogen trifluoride gas (NF₃ gas) or sulfur hexafluoride gas(SF₆ gas). The process gas may further include a hydrofluorocarbon gascomponent. The hydrofluorocarbon gas component is gas of thehydrofluorocarbons listed above. The process gas may further include ahalogen gas component containing a halogen component other than fluorinecomponent. The halogen gas component is, for example, Cl₂ gas and/or HBrgas.

An exemplary process gas includes a phosphorus gas component, afluorocarbon gas component, a hydrogen gas component, and an oxygen gascomponent (for example, O₂ gas), or is substantially composed of thesegases. Another exemplary process gas includes a phosphorus gascomponent, a carbon-free fluorine gas component, a fluorocarbon gascomponent, a hydrogen gas component, a hydrofluorocarbon gas component,and a halogen gas component containing a halogen component other thanfluorine component, or is substantially composed of these gases.

In another embodiment, the process gas includes the phosphorus gascomponent described above, the fluorine gas component described above,the hydrofluorocarbon gas component described above, and the halogen gascomponent containing a halogen component other than fluorine componentdescribed above, or is substantially composed of these gases.

In one embodiment, the process gas may contain a first gas and a secondgas. The first gas does not contain phosphorus component. In otherwords, the first gas is all the gases excluding the phosphorus gascomponent in the process gas. The first gas may contain a halogencomponent. The first gas may contain gas of at least one of thehalogen-containing molecules described above. The first gas may furthercontain a carbon component and a hydrogen component. The first gas mayfurther contain gas of a hydrogen-containing compound and/or gas of acarbon-containing compound. The first gas may further contain an oxygencomponent. The first gas may contain O₂ gas. 2 0 Alternatively, thefirst gas may be free of oxygen. The second gas is a gas containingphosphorus component. Specifically, the second gas is the phosphorus gascomponent described above. The second gas may contain gas of the atleast one of the phosphorus compounds described above.

In the process gas used in Step STP, the ratio of the flow rate of thesecond gas to the flow rate of the first gas may be above 0 and 0.5 orless. The ratio may be 0.075 or more and 0.3 or less. The ratio may be0.1 or more and 0.25 or less.

With reference to FIG. 5, the process gas is supplied to the chamber 10in Step STP. In Step STP, the gas pressure in the chamber 10 is adjustedto a predetermined value. In Step STP, the gas pressure in the chamber10 may be adjusted to 5 mTorr (0.65 Pa) or more and 100 mTorr (13.3 Pa)or less. In Step STP, a radio-frequency power HF is supplied to formplasma from the process gas in the chamber 10. As depicted with a solidline in FIG. 5, a continuous wave of radio-frequency power HF may beapplied in Step STP. In Step STP, the radio-frequency power HF may bereplaced with the radio-frequency power LF. In Step STP, both theradio-frequency power HF and the bias electric power may be supplied. Asshown by the solid line in FIG. 5, a continuous wave of bias electricpower may be applied to the bottom electrode 18 in Step STP. The levelof the radio-frequency power HF may be adjusted to 2 kW or more and 10kW or less. If the radio-frequency power LF is used as the bias electricpower, the level of the radio-frequency power LF may be adjusted to 2 kWor more. The level of the radio-frequency power LF may be adjusted to 10kW or more.

In Step STP, the controller 80 controls the gas supply unit to supplythe process gas into the chamber 10. The controller 80 also controls theevacuation system 50 such that the gas pressure in the chamber 10 isregulated within a predetermined pressure. In addition, the controller80 controls the radio-frequency power source 62 and the bias powersource 64 to supply the radio-frequency power HF, radio-frequency powerLF, or the radio-frequency power HF and the bias electric power.

In Step ST2, the controller 80 controls the gas supply unit to supplythe process gas into the chamber 10. The controller 80 also controls theevacuation system 50 to keep the gas pressure in the chamber 10 at apredetermined value. In addition, the controller 80 controls theradio-frequency power source 62 and the bias power source 64 to supplythe radio-frequency power HF, radio-frequency power LF, or theradio-frequency frequency power HF and the bias electric power.

In an embodiment of the method MT, the substrate W may be kept at atemperature of 0° C. or less at the start of Step ST2 (or Step STP). Atsuch a temperature, the etching rate of the silicon-containing film SFon the substrate W increases in Step ST2. The controller 80 may controla chiller to adjust the temperature of the substrate W 2 5 at the startof Step ST2. In Step ST2 (or Step STP), the temperature of the substrateW may be 200° C. or less. A temperature of 200° C. or less of thesubstrate Win Step ST2 (or Step STP) ensures supply of an etchant, i.e.,phosphorus chemical species into the bottom of the recesses formed inthe silicon-containing film SF.

According to the Arrhenius equation that defines reaction rate increasewith temperature, the amount of side etching decreases at lowtemperatures (for example, 0° C. or lower). At low temperatures, thevolatility (which is a measure indicating how a material vaporizes) ofthe protective film (P-O) decreases. As described above, because of lowvolatility (chemically strong), the protective film preventing the sidewall from being laterally etched is more effective at low temperatures.In addition, the high-aspect ratio etching tends to increase ion energy.The inventor of the present disclosure recognizes the benefit of theetching temperature that should be low in order to enhance theeffectiveness of the protective film. In the present disclosure,therefore, the protective film having a low volatility (which isachieved by controlling the temperature of the substrate W to a lowtemperature) is more desirable because it helps to reduce etching of theside wall (bowing).

In one embodiment, the method MT may further involve Step STT. Step STTmay be executed prior to Step ST2 (or Step STP). The temperature of thesubstrate W is set to 0° C. or less in Step STT. The temperature of thesubstrate W at the start of Step ST2 is set in Step STT. The controller80 may control the chiller to set the temperature of the substrate W inStep STT.

In Step ST2, the silicon-containing film SF is etched by halogenchemical species in the plasma generated from the process gas. In oneembodiment, the unmasked portion (portion exposed to plasma) of thesilicon-containing film SF is etched as shown in FIG. 4A.

If the process gas contains a compound functioning as a phosphoruscomponent and a halogen component, such as PF₃, the halogen chemicalspecies derived from the compound contributes to etching of thesilicon-containing film SF. The compound containing phosphorus componentand halogen component, such as PF₃, can accordingly enhance the etchingrate of the silicon-containing film SF in Step ST2.

In Step ST3, a protective film PF is formed on the side wall of therecess formed by etching in Step ST2 in the silicon-containing film SF(refer to FIG. 4A). The protective film PF is formed from the chemicalspecies included in the plasma generated from the process gas in thechamber 10 in Step STP. Step ST3 and Step ST2 may be carried out at thesame time. Referring to FIG. 4A, the protective film PF according to oneembodiment is formed such that its thickness decreases toward the depthof the recess formed in the silicon-containing film SF.

The protective film PF contains silicon and phosphorus componentcontained in the process gas used in Step STP. In one embodiment, theprotective film PF may further contain carbon and/or hydrogen containedin the process gas. In one embodiment, the protective film PF mayfurther contain oxygen contained in the process gas or thesilicon-containing film SF. In one embodiment, the protective film PFmay contain bonds between phosphorus and oxygen.

FIGS. 6A and 6B illustrate the results of XPS analysis of protectivefilms PF formed in an experimental example that involves etching of asilicon oxide film and a silicon nitride film, respectively, in StepSTP. FIGS. 6A and 6B illustrate P2p spectra. The conditions of theexperimental example in Step STP are as follows:

<Conditions in Step STP>

Gas pressure in chamber 10: 100 mTorr (13.33 Pa)

Process gas: 50 sccm of PF₃ gas and 150 sccm of Ar gas

Radio-frequency power HF (continuous wave): 40 MHz, 4500 W

Radio-frequency power LF (continuous wave): 400 kHz, 7000 W

Substrate temperature (temperature of substrate support before etching):−70° C.

Execution time in Step STP: 30 seconds

According to the experimental results of the etching of the siliconoxide film in Step STP, the results of the XPS analysis of theprotective film PF show a peak assigned to a Si—O bond and a peakassigned to a P—O bond as illustrated in FIG. 6A. According to theexperimental results of the etching of the silicon nitride film in StepSTP, the results of the XPS analysis of the protective film PF show apeak assigned to a Si—P bond and a peak assigned to a P—N bond asillustrated in FIG. 6B.

In one embodiment, the plasma of the process gas described abovecontains a plasma generated from hydrogen fluoride component. In oneembodiment, the largest amount of chemical species included in theplasma generated from the process gas may be hydrogen fluoridecomponent. In the presence of the phosphorous chemical species generatedfrom the phosphorus gas component (the gas containing the phosphorouscompound described above) on a surface of the substrate W, adsorption ofhydrogen fluoride component, that is, etchant to the substrate W ispromoted. More specifically, in the presence of the phosphorous chemicalspecies generated from the phosphorus gas component on a surface of thesubstrate W, supply of the etchant to the bottom of the hole (recess) ispromoted and the etching rate of the silicon-containing film SF isthereby enhanced.

If the process gas does not contain phosphorus component, thesilicon-containing film SF is etched also in the lateral direction asshown in FIG. 4B. As a result, the width of the recess formed in thesilicon-containing film SF increases partly. For example, the width ofthe recess formed in the silicon-containing film SF increases partly inthe vicinity of the mask MK.

In the method MT, the protective film PF is formed on the side wall ofthe recess formed in the silicon-containing film SF during the etching.The protective film PF protects the side wall and allows thesilicon-containing film SF to be etched at the same time. Lateraletching is accordingly reduced during the plasma etching of thesilicon-containing film SF in the method MT.

In one embodiment, one or more periods of Steps ST2 and ST3 may beexecuted while Step STP is being continued, in detail, while plasma isgenerated from the process gas in Step STP. Step STP may involve atleast two periods.

In one embodiment, the pulsed bias electric power may be applied fromthe bias power source 64 to the bottom electrode 18 in Step STP, asdepicted with broken lines in FIG. 5. In detail, the pulsed biaselectric power may be applied from the bias power source 64 to thebottom electrode 18, in the presence of plasma generated from theprocess gas in the chamber 10. In this embodiment, thesilicon-containing film SF is etched mainly within the term H in theperiod of the pulsed bias electric power in Step ST2. The protectivefilm PF is formed mainly within the term L in the period of the pulsedbias electric power in Step ST3.

If the bias electric power is radio-frequency power LF, theradio-frequency power LF may be adjusted to 2 kW or more during the termH of the period of pulsed bias electric power. Alternatively, theradio-frequency power LF may be adjusted to 10 kW or more during theterm H of the period of pulsed bias electric power.

In one embodiment, the pulsed waves of the radio-frequency power HF maybe applied in Step STP, as depicted with broken lines in FIG. 5. Theradio-frequency power HF may be adjusted to 1 kW or more and 10 kW orless within the term H in the period of the pulsed radio-frequency powerHF. With reference to FIG. 5, the period of the pulsed waves of theradio-frequency power HF may be in synchronization with the period ofthe pulsed bias electric power. With reference to FIG. 5, the term H inthe period of the pulsed radio-frequency power HF may be insynchronization with the term H in the period of the pulsed biaselectric power. Alternatively, the term H in the period of the pulsedradio-frequency power HF need not be in synchronization with the term Hin the period of the pulsed bias electric power. The term H of theperiod of the pulsed radio-frequency power HF may be the same as ordifferent from the term H of the period of the pulsed bias electricpower.

FIG. 7 is an exemplary timing chart in the method according to anexemplary embodiment where the horizontal axis indicates time while thevertical axis indicates the level of the radio-frequency power HF, thelevel of the bias electric power, supply of a first gas, and supply of asecond gas. The level “L” in the radio-frequency power HF indicates thatno radio-frequency power HF is supplied or the level of theradio-frequency power HF is lower than the level “H”. The level “L” inthe bias electric power indicates that no bias electric power issupplied to the bottom electrode 18 or the level of the bias electricpower is lower than the level “H”. The symbol “ON” in the supply of thefirst gas indicates that the first gas is being supplied into thechamber 10 whereas the symbol “OFF” indicates that the first gas is notbeing supplied into the chamber 10. The symbol “ON” in the supply of thesecond gas indicates that the second gas is being supplied into thechamber 10 whereas the symbol “OFF” indicates that the second gas is notbeing supplied into the chamber 10.

With reference to FIG. 7, the first gas and the second gas mayalternately supplied to the chamber 10 in Step STP. The etching ofsilicon-containing film SF in Step ST2 is performed, mainly, duringsupply of the first gas to the chamber 10. The forming of the protectivefilm PF in Step ST3 is performed, mainly, during supply of the secondgas to the chamber 10.

Continuous radio-frequency power HF may be applied in Step STP, asdepicted with a solid line in FIG. 7. Alternatively, pulsedradio-frequency power HF may be applied in Step STP, like the pulsedradio-frequency power HF shown in FIG. 5. Pulsed radio-frequency powerHF is depicted with broken lines in FIG. 7. The term H within the periodof the pulsed radio-frequency power HF is in synchronization with orpartially overlap with the term during which the first gas is suppliedto the chamber 10. In contrast, the term L within the period of thepulsed radio-frequency power HF is in synchronization with or partiallyoverlap with the term during which the second gas is supplied to thechamber 10.

Alternatively, continuous bias electric power may be applied to thebottom electrode 18 in Step STP as shown by the solid line in FIG. 7.Alternatively, pulsed bias electric power may be applied to the bottomelectrode 18 in Step STP, like the pulsed bias electric power shown inFIG. 5. The pulsed bias electric power is depicted with the broken linesin FIG. 7. The term H within the period of the pulsed bias-frequencypower is in synchronization with or partially overlap with the termduring which the first gas is supplied to the chamber 10. The term Lwithin the period of the pulsed bias-frequency power is insynchronization with or partially overlap with the term during which thesecond gas is supplied to the chamber 10.

The effect achieved by applying pulsed bias electric power duringetching does not lie in deposition nor mainly in etching, but lies inthat an etching phase and a deposition phase separately occur. When biaselectric power is supplied to the bottom electrode, etching mainlyoccurs. On the other hand, when bias electric power is not supplied tothe bottom electrode, deposition mainly occurs. Applying the pulsed biaselectric power achieves an etching phase and a deposition phase thatoccur alternately. In the etching phase, etching occurs after aprotective film is formed to protect the side wall of the recess (hole)from side etching. Thus, a continuous phase including formation(deposition) of a protective film and subsequent etching enablescontrolled etching that reduces bowing of the side wall and meanwhilecontinuously increases the depth of the recess (hole). Variations in theduty cycle of pulses ((bias ON time)/(bias ON time+bias OFF time))provide a mechanism of controlling the balance between the etching phaseand the deposition phase. A longer bias OFF time facilitates formationof a thicker protective film and provides further protection from sideetching. A longer bias ON time increases the etching rate and controlsthe time taken to reach a desired etching depth.

A first experiment for evaluation of the method MT will now beexplained. Multiple sample substrates were prepared for the firstexperiment. Each sample substrate had a silicon oxide film and a maskformed on the silicon oxide film. The mask was made of an amorphouscarbon film. In the first experiment, Step STP in the method MT wasapplied to each sample substrate. The process gases used for thesesample substrates contained PF₃ gas at different flow rates. Otherconditions in Step STP are shown below, where the flow rates of the PF₃gas were 0 sccm, 15 sccm, 30 sccm, 50 sccm, and 100 sccm, respectively,in other words, the ratios of the flow rate of the second gas to theflow rate of the first gas were 0, 0.075, 0.15, 0.25, and 0.5,respectively.

<Conditions in Step STP>

Gas pressure in chamber 10: 25 mTorr (3.3 Pa)

Process gas: 50 sccm of CH₄ gas, 100 sccm of CF₄ gas, and 50 sccm of O₂gas

Radio-frequency power HF (continuous wave): 40 MHz, 4500 W

Radio-frequency power LF (continuous wave): 400 kHz, 7000 W

Sample substrate temperature (temperature of substrate support beforeetching): −30° C.

Execution time in Step STP: 600 seconds

In the first experiment, the maximum width of the recess formed in thesilicon oxide film, the etching rate of the silicon oxide film, and theetching selectivity of each sample substrate were determined. Theetching selectivity is a value of the etching rate of the silicon oxidefilm divided by the etching rate of the mask. The relation between theflow rate of the PF₃ gas in the process gas used in Step STP and theetching rate of the silicon oxide film was then determined. The relationbetween the flow rate of the PF₃ gas in the process gas used in Step STPand the maximum width of the recess in the silicon oxide film was alsodetermined. In addition, the relation between the flow rate of the PF₃gas in the process gas used in Step STP and the etching selectivity was2 0 determined. FIG. 8 shows the relation between the flow rate of thePF₃ gas of the process gas and the etching rate of the silicon oxidefilm. FIG. 9 shows the relation between the flow rate of the PF₃ gas ofthe process gas and the maximum width of the recess formed in thesilicon oxide film. FIG. 10 shows the relation between the flow rate ofthe PF₃ gas of the process gas and the etching selectivity.

FIGS. 8 and 10 demonstrate that the etching rate and the etchingselectivity of the silicon oxide film increase in the case that theprocess gas contains a phosphorus component, in other words, the ratioof the flow rate is greater than 0. FIG. 10 also demonstrates that theetching selectivity is considerably high in the case that the flow rateof PF₃ gas in the process gas is in the range from 15 sccm or more to 50sccm or less or 60 sccm, in other words, in the case that the ratio ofthe flow rate is in the range from 0.075 or more to 0.25 or less or 0.3.FIG. 8 demonstrates that the etching rate at a flow rate of the PF₃ gasin the process gas of 20 sccm or more or at a ratio of the flow rate of0.1 or more is about 1.5 times the etching in the case that no PF₃ isadded.

FIG. 9 demonstrates that a process gas containing a phosphorus componentcauses decrease in the maximum width of the recess formed in the siliconoxide film, in other words, reduces partial expansion of the recess inthe silicon oxide film. At a flow rate of the PF₃ gas in the process gasof 50 sccm or more, partial expansion of the recess in the silicon oxidefilm can be reduced.

In FIG. 9, the horizontal axis indicates the flow rate of the PF₃ gas,and the vertical axis indicates the maximum width of the etching recess(hole). The amount of fluorine component, that is, etchant increaseswith the flow rate of the PF₃ gas, and the increase in etchant causesincrease in etching rate (see FIG. 8). As the flow rate of the PF₃ gasincreases, the etching rate in the vertical direction increases.However, although the flow rate of PF₃ gas increases, the maximum widthof the recess (hole) is substantially constant (actually, slightlydecreases) up to 15 sccm (7.5%). At the flow rate exceeding 15 sccm(7.5%), the maximum width of the recess (hole) decreases. The use of thephosphorus gas component during etching thus effectively reduces sideetching (bowing).

The protective film containing P—O bonds has a low volatility (that is,chemically strong). As recognized by the inventor of the presentdisclosure, the presence of the protective film having P—O bonds iseffective in protecting the side wall of the recess in thesilicon-containing film from erosion by ions having relatively lowenergy. On the other hand, ions impinging on the bottom of the recess(hole) has high energy and therefore removes (etches) the bottom of therecess, in spite of the protective film formed on the bottom of therecess. The protective film having P—O bonds thus has a selectiveprotective function for undesired etching of the side wall. This isbecause the protective film having P—O bonds is chemically strong enoughto avoid being removed by ions with low energy colliding against theside wall at a shallow angle. On the other hand, ions with high energycolliding against the bottom of the recess on direct impact have highenergy enough to etch away the protective film having P—O bonds at thebottom of the recess. Consequently, this reduces bowing of the side walland enables etching with a high aspect ratio.

A second experiment for evaluation of the method MT will now beexplained. Multiple sample substrates were prepared for the secondexperiment. Each sample substrate had a silicon-containing film and amask formed on the silicon-containing film. The silicon-containing filmwas a stack of alternately stacked silicon oxide sublayers and siliconnitride sublayers. The mask was made of an amorphous carbon film. In thesecond experiment, Step STP in the method MT was applied to each samplesubstrate. The process gases used for these sample substrates containedPF₃ gas at different flow rates. Other conditions in Step STP are shownbelow, where the flow rates of the PF₃ gas were 0 sccm, 5 sccm, 20 sccm,and 30 sccm, respectively.

<Conditions in Step STP>

Gas pressure in chamber 10: 25 mTorr (3.3 Pa)

Process gas: a gas mixture including a fluorine gas component, ahydrofluorocarbon gas component, a halogen gas component containing ahalogen component other than fluorine component, and PF₃ gas

Radio-frequency power HF: 40 MHz, 5500 W

Radio-frequency power LF: 400 kHz, 8400 W

Sample substrate temperature (temperature of substrate support beforeetching): −30° C.

In the second experiment, the etching rate of the silicon-containingfilm, the etching rate of the mask, and the etching selectivity for eachsample substrate were determined. The etching selectivity is a value ofthe etching rate of the silicon-containing film divided by the etchingrate of the mask. In the second experiment, the relation between theflow rate of PF₃ gas and each of the etching rate of thesilicon-containing film, the etching rate of the mask, and the etchingselectivity was determined. FIG. 11 shows the relation between the flowrate of PF₃ gas and each of the etching rate of the silicon-containingfilm, the etching rate of the mask, and the etching selectivity in thesecond experiment. As illustrated in FIG. 11, the result of the secondexperiment has demonstrated that even when the flow rate of PF₃ gasadded to the process gas is small, the etching rate of thesilicon-containing film increases. It has also been demonstrated thateven when the flow rate of PF₃ gas added to the process gas is small,the selectivity increases.

Referring to FIG. 12, another exemplary etching method of the presentdisclosure will now be described. The etching method illustrated in FIG.12 (hereinafter referred to as “method MT2”) is applied to a substratehaving a silicon-containing film. The substrate to which the method MT2is applied is, for example, the substrate W illustrated in FIG. 2 andhas a silicon-containing film SF. In the method MT2, thesilicon-containing film SF is etched. The silicon-containing film etchedin the method MT2 is the silicon-containing film SF described above inconnection with the method MT. The substrate W to which the method MT2is applied may further include a mask MK and an underlying region UR asdescribed above in connection with the method MT.

In the method MT2, a plasma treatment system is used for etching thesilicon-containing film SF. The plasma treatment system used in themethod MT2 is, for example, the plasma treatment system 1 describedabove.

The method MT2 applied to the substrate W illustrated in FIG. 2 usingthe plasma treatment system 1 will now be described as an example. Whenthe plasma treatment system 1 is used, the method MT2 may be performedin the plasma treatment system 1 under the control of the controller 80on each component in the plasma treatment system 1. The control on eachcomponent in the plasma treatment system 1 by the controller 80 forperforming the method MT2 will be described below.

In the following description, FIG. 12 as well as FIG. 13, FIG. 14, andFIG. 15 will be referred to. FIG. 13 and FIG. 14 each are a partiallyenlarged cross-sectional view of an exemplary substrate to which themethod shown in FIG. 12 is applied. FIG. 2 0 15 is another exemplarytiming chart according to the present disclosure where the horizontalaxis indicates time while the vertical axis indicates the level of theradio-frequency power HF, the level of the bias electric power, and thesupply of the process gas, in the same manner as the vertical axis inFIG. 7. The level “L” in the radio-frequency power HF indicates that noradio-frequency power HF is supplied or the level of the radio-frequencypower HF is lower than the level “H”. The level “L” in the bias electricpower indicates that no bias electric power is applied to the bottomelectrode 18 or the level of the bias electric power is lower than thelevel “H”. The symbol “ON” in the supply of the process gas indicatesthat the process gas is being supplied into the chamber 10 whereas thesymbol “OFF” indicates that the process gas is not being supplied intothe chamber 10.

With reference to FIG. 12, the method MT2 starts with Step ST21. In StepST21, the substrate W is disposed in the chamber 10, in the same manneras Step ST1 in the method MT.

In the method MT2, Step ST22 is then performed. In Step ST22, thesilicon-containing film SF is etched by a chemical species in plasmagenerated from the process gas in the chamber 10.

The process gas used in Step ST22 includes a hydrogen fluoride gascomponent, a phosphorus gas component, and a carbon gas component. Theprocess gas may further include a rare gas. The process gas may furtherinclude a fluorine-free halogen gas component. The fluorine-free halogengas component contains, for example, at least one of Cl₂, HBr, and BCl₃.The process gas may further include an oxygen gas component. The oxygengas component contains, for example, O₂.

In the process gas used in Step ST22, the phosphorus gas component isthe phosphorus gas component described above in connection with themethod MT. In the process gas used in Step ST22, the carbon gascomponent contains at least one of hydrocarbon (C_(x)H_(y)),hydrofluorocarbon (C_(s)H_(t)F_(u)), and fluorocarbon (C_(v)F_(w)),where x, y, s, t, u, v, and w each are a natural number. The hydrocarbonis, for example, at least one of CH₄, C₃H₆, and the like. Thehydrofluorocarbon is, for example, at least one of CH₂F₂, CHF₃, CH₃F,C₂HF₅, C₃H₂F₄, C₃H₂F₆, C₄H₂F₆ and the like. The fluorocarbon is, forexample, at least one of CF₄, C₂F₆, C₃F₆, C₃F₈, C₄F₆, C₄F₈, C₅F₈, andthe like. When a carbon gas component containing at least two carbonatoms is used, the effect of protecting the side wall surface thatdefines the recess in the mask MK and the silicon-containing film SF maybe increased.

In one embodiment, in the process gas used in Step ST22, the flow rateof the hydrogen fluoride gas component may be largest among the flowrate of the hydrogen fluoride gas component, the flow rate of thephosphorus gas component, and the flow rate of the carbon gas component.When the process gas used in Step ST22 includes a rare gas, the flowrate of the hydrogen fluoride gas component may be largest among theflow rates of all the gases in the process gas, excluding the rare gas.The proportion of the flow rate of the hydrogen fluoride gas componentto the flow rate of the process gas if the process gas does not includea rare gas, or to the flow rate of the process gas excluding a rare gasif the process gas includes a rare gas, may be 50% or more and less than99%. The proportion of the flow rate of the phosphorous gas component tothe flow rate of the process gas if the process gas does not include arare gas, or to the flow rate of the process gas excluding a rare gas ifthe process gas includes a rare gas, may be 1% or more and 20% or less.In the process gas, the proportion of the flow rate of the phosphorusgas component in the sum of the flow rate of the hydrogen fluoride gascomponent, the flow rate of the phosphorus gas component, and the flowrate of the carbon gas component may be 2% or more. The proportion ofthe flow rate of the carbon gas component to the flow rate of theprocess gas if the process gas does not include a rare gas, or to theflow rate of the process gas excluding a rare gas if the process gasincludes a rare gas, may be above 0% and 20% or less.

In one embodiment, in the process gas used in Step ST22, the proportionof the flow rate of the halogen gas component in the sum of the flowrate of the hydrogen fluoride gas, the flow rate of the phosphorus gascomponent, the carbon gas component, and the flow rate of the halogengas component may be above 0% and 10% or less.

In Step ST22, the controller 80 controls the gas supply unit to supplythe process gas into the chamber 10. The controller 80 also controls theevacuation system 50 such that the gas pressure in the chamber 10 isregulated within a predetermined pressure. In addition, the controller80 controls the plasma generator to generate plasma from the processgas. In the plasma treatment system 1, the controller 80 controls theradio-frequency power source 62 and the bias power source 64 to supplythe radio-frequency power HF, the radio-frequency power LF, or theradio-frequency power HF and the bias electric power.

In one embodiment, the substrate support 14 (specifically, theelectrostatic chuck 20) in Step ST22 may be kept at a temperature of 0°C. or less or −40° C. or less. At such a temperature, the etching rateof the silicon-containing film SF on the substrate W increases in StepST22. The controller 80 may control a chiller to adjust the temperatureof the substrate support 14 in Step ST22.

In Step ST22, as illustrated in FIG. 13 and FIG. 14, thesilicon-containing film SF is etched by the halogen chemical species inplasma generated from the process gas. The halogen chemical speciesinclude a fluorine chemical species generated from the hydrogen fluoridegas component. Hydrogen fluoride has a small molecular weight, and thesputtering effect on the mask MK by a chemical species generated fromhydrogen fluoride is small so that etching of the mask MK is suppressed.The plasma generated from the hydrogen fluoride gas component thereforecan etch the silicon-containing film SF while suppressing etching of themask MK. The plasma generated from the hydrogen fluoride gas componentcan also increase the etching rate of the silicon-containing containingfilm SF. In addition, a chemical species generated from the carbon gascomponent protects the mask MK. The more carbon atoms are contained inthe molecule in the carbon gas component, the higher the effect ofprotecting the mask MK is. Furthermore, the plasma generated from thephosphorus gas component may suppress etching of the mask MK. Inaddition, in the presence of the phosphorous chemical species generatedfrom the phosphorus gas component on a surface of the substrate W,adsorption of a chemical species generated from hydrogen fluoride gascomponent, that is, etchant to the substrate W is promoted. Morespecifically, in the presence of the phosphorous chemical speciesgenerated from the phosphorus gas component on a surface of thesubstrate W, supply of the etchant to the bottom of the hole (recess) ispromoted and the etching rate of the silicon-containing film SF isthereby enhanced. The method MT2 thus can increase the etching rate andthe etching selectivity in plasma etching of the silicon-containing filmSF. When the phosphorus gas component in the process gas contains thehalogen component as described above and/or when the process gasincludes the halogen gas component described above, the etching rate ofthe silicon-containing film SF is further enhanced. Instead of thehydrogen fluoride gas component, a hydrogen gas component and a fluorinegas component may be used with a phosphorus gas component to achieve aneffect similar to the effect achieved by the hydrogen fluoride gascomponent. The hydrogen gas component is, for example, H₂ gas and/orhydrofluorocarbon gas. An example of the fluorine gas component isfluorocarbon gas.

In Step ST22, phosphorous chemical species (ions and/or radicals) aresupplied from plasma generated from the phosphorus gas component to thesubstrate W. With reference to FIG. 13, the phosphorous chemical speciesmay form a protective film PF containing phosphorous on the surface ofthe substrate W. The protective film PF may further contain carbonand/or hydrogen contained in the process gas. In one embodiment, theprotective film PF may further contain oxygen contained in the processgas or in the silicon-containing film SF. In one embodiment, theprotective film PF may include phosphorous-oxygen bonds.

Instead of forming the protective film PF or in addition to forming theprotective film PF, the phosphorous chemical species may form phosphorusbonds with a source included in the silicon-containing film SF at theside wall surface defining a recess in the silicon-containing film SF.When the silicon-containing film SF includes a silicon oxide film, thephosphorous chemical species forms phosphorous-oxygen bonds at the sidewall surface of the silicon-containing film SF. In FIG. 14, phosphorousis depicted as “P” surrounded by a circle. In Step ST22, the side wallsurface of the silicon-containing film SF is inactivated (or passivated)by the phosphorous chemical species. In other words, the side wallsurface of the silicon-containing film SF undergoes passivation.

The method MT2 thus reduces etching of the side wall surface of thesilicon-containing containing film SF and the lateral expansion of therecess in the silicon-containing film SF.

When the mask MK contains carbon, the phosphorous chemical species mayform carbon-phosphorous bonds on the surface of the mask MK. Thecarbon-phosphorous bonds have higher bonding energy than carbon-carbonbonds in the mask MK. The method MT2 thus can protect the mask MK inplasma etching of the silicon-containing film SF.

As illustrated in FIG. 15, in Step ST22, continuous or pulsedradio-frequency power HF may be supplied, in the same manner as thecontinuous or pulsed radio-frequency frequency power HF in Step STPexplained with reference to FIG. 7. Alternatively, in

Step ST22, continuous or pulsed bias electric power may be supplied, inthe same manner as the continuous or pulsed bias electric power in StepSTP explained with reference to FIG. 7.

Specifically, in one embodiment, as depicted by a broken line in FIG.15, the pulsed bias electric power may be applied from the bias powersource 64 to the bottom electrode 18 in Step ST22. In other words, whenplasma generated from the process gas is present in the chamber 10, thepulsed bias electric power may be applied from the bias power source 64to the bottom electrode 18. In this embodiment, the silicon-containingfilm SF is etched mainly within the term H in the period of the pulsedbias electric power in Step ST22. The formation and/or the passivationof the protective film PF in Step ST22 is performed mainly in the term Lin the period of the pulsed bias electric power.

In one embodiment, as depicted by a broken line in FIG. 15, the pulsedradio-frequency power HF may be supplied in Step ST22. As illustrated inthe FIG. 15, the period of the pulsed radio-frequency power HF may besynchronized with the period of the pulsed bias electric power. Asillustrated in the FIG. 15, the term H in the period of the pulsedradio-frequency power HF may be in synchronization with the term H inthe period of the pulsed bias electric power. Alternatively, the term Hin the period of the pulsed radio-frequency power HF may not be insynchronization with the term H in the period of the pulsed biaselectric power. The length of the term H in the period of the pulsedradio-frequency power HF may be the same as or different from the lengthof the term H in the period of the pulsed bias electric power.

Experiments for evaluation of the method MT2 will now be explained. Theexperiments described below are not intended to limit the presentdisclosure.

(Third to Sixth Experiments)

In third to sixth experiments, multiple sample substrates having thesame structure as the substrate W does illustrated in FIG. 2 wereprepared. Each sample substrate had a silicon-containing film and a maskformed on the silicon-containing film. The silicon-containing film had amultilayer configuration including alternately stacked silicon oxidesublayers and silicon nitride sublayers. The mask was made of anamorphous carbon film. In each of the third to sixth experiments, theplasma treatment system 1 was used to generate a plasma from the processgas and etch the silicon-containing film of the sample substrate. Theprocess gas used in the third experiment contained H₂ gas component, ahydrofluorocarbon gas component, a fluorocarbon gas component, afluorine gas component, and a halogen gas component. The process gasused in the fourth experiment contained PF₃ gas in addition to theprocess gas in the third experiment. The process gas used in the fifthexperiment contained a hydrogen fluoride gas component, a fluorocarbongas, and oxygen gas. The process gas used in the sixth experimentcontained a hydrogen fluoride gas component, a fluorocarbon gas, and PF₃gas. Other conditions in the third to sixth experiments are shown below.

<Other Conditions in Third to Sixth Experiments>

Gas pressure in chamber 10: 27 mTorr (3.6 Pa)

Radio-frequency power HF (continuous wave): 40 MHz, 4400 W

Radio-frequency power LF (continuous wave): 400 kHz, 6000 W

Temperature of substrate support 14: −40° C.

In each of the third to sixth experiments, the etching rate of thesilicon-containing film, the etching selectivity, and the maximum width(bowing CD) of the recess formed in the silicon-containing film weredetermined from the result of etching of the silicon-containing film.The etching selectivity is a value of the etching rate of thesilicon-containing film divided by the etching rate of the mask. Theetching rates of the silicon-containing film in the third to sixthexperiments were 310 nm/min, 336 nm/min, 296 nm/min, and 597 nm/min,respectively. The etching selectivities in the third to sixthexperiments were 3.24, 4.1, 6.52, and 7.94, respectively. The bowing CDsin the third to sixth experiments were 106 nm, 104 nm, 128 nm, and 104nm, respectively. The results in the third to sixth experiments havedemonstrated that both of a higher etching rate and a high etchingselectivity were obtained and a smaller bowing CD was obtained in thefourth and sixth experiments, compared with the third and fifthexperiments. In particular, in the sixth experiment, the etching ratewas about twice the etching rate in the third experiment. It has beendemonstrated that the use of the process gas including a hydrogenfluoride gas component, a carbon gas component, and a phosphorus gascomponent in plasma etching of the silicon-containing film can enhancethe etching rate and the etching selectivity. It has also beendemonstrated that the use of the process gas including a hydrogenfluoride gas component, a carbon gas component, and a phosphorus gascomponent in plasma etching of the silicon-containing film reduces thelateral expansion of the recess in the silicon-containing film.

(Seventh Experiment)

In a seventh experiment, the same sample substrates as the samplesubstrates prepared in the third to sixth experiments were prepared. Inthe seventh experiment, the plasma treatment system 1 was used togenerate plasma from the process gas and etch the silicon-containingfilm of each sample substrate. The process gas used in the seventhexperiment included a hydrogen fluoride gas component and a fluorocarbongas component. In the seventh experiment, the proportions of the flowrate of PF₃ gas in the process gases used for the sample substrates weredifferent. Here, the proportion of the flow rate of PF₃ gas is theproportion of the flow rate of the PF₃ gas to the flow rate of theprocess gas. Other conditions in the seventh experiment are the same asthe corresponding conditions in the third to sixth experiments describedabove.

In the seventh experiment, the etching rate of the silicon-containingfilm was determined from the result of etching of the silicon-containingfilm of each sample substrate. The relation between the proportion ofthe flow rate of PF₃ gas and the etching rate of the silicon-containingfilm was determined. The result is illustrated in FIG. 16. FIG. 16demonstrates that the etching rate is high when the proportion of theflow rate of PF₃ gas to the flow rate of the process gas is 2% or more(or 2.5% or more). In other words, a high etching rate is achieved whenthe flow rate of the phosphorus gas component relative to the flow rateof the process gas including the hydrogen fluoride gas component, thecarbon gas component, and the phosphorus gas component is 2% or more (or2.5% or more).

(Eighth to Eleventh Experiments)

In each of an eighth experiment and a ninth experiment, multiplesubstrates each having a silicon oxide film were prepared. In each ofthe eighth experiment and the ninth experiment, the plasma treatmentsystem 1 was used to generate a plasma from the process gas and etch thesilicon oxide film of each sample substrate. In each of the eighthexperiment and the ninth experiment, the temperatures of the substratesupport 14 in etching of the silicon oxide films of the samplesubstrates were different. In each of a tenth experiment and an eleventhexperiment, multiple substrates each having a silicon nitride film wereprepared. In each of the tenth experiment and the eleventh experiment,the plasma treatment system 1 was used to generate plasma from theprocess gas and etch the silicon nitride film of each sample substrate.In each of the tenth experiment and the eleventh experiment, thetemperatures of the substrate support 14 in etching of the siliconnitride films of the sample substrates were different. The process gasused in each of the eighth to eleventh experiments contained a hydrogenfluoride gas component and a fluorocarbon gas. The proportion of theflow rate of PF₃ gas to the flow rate of the process gas used in theeighth experiment and the tenth experiment was 2.5%. The process gasused in the ninth experiment and the eleventh experiment contained noPF₃ gas. Other conditions in the eighth to eleventh experiments were thesame as the corresponding conditions in the third to sixth experimentsdescribed above.

In the eighth experiment and the ninth experiment, the etching rate ofthe silicon oxide film was determined from the result of etching of thesilicon oxide film of each sample substrate. In the tenth experiment andthe eleventh experiment, the etching rate of the silicon nitride filmwas determined from the result of etching of the silicon nitride film ofeach sample substrate. FIG. 17 illustrates the relation between thetemperature of the substrate support 14 set in the eighth to eleventhexperiments and the resulting etching rate. In FIG. 17, No. 8, No. 9,No. 10, and No. 11 indicate the results of the eighth to eleventhexperiments, respectively. FIG. 17 demonstrates that the etching rate ofthe silicon oxide film is higher in the eighth experiment using theprocess gas including PF₃ gas than the etching rate of the silicon oxidefilm in the ninth experiment using the process gas including no PF₃ gas.The result in the eighth experiment also has demonstrated that theetching rate of the silicon oxide film is higher when the temperature ofthe substrate support 14 is set to 0° C. or less in the case of usingthe process gas including PF₃ gas. It has also been demonstrated thatthe etching rate of the silicon oxide film is significantly high whenthe temperature of the substrate support 14 is set to −40° C. or less inthe case of using the process gas including PF₃ gas.

(Twelfth Experiment and Thirteenth Experiment)

In a twelfth experiment, the plasma treatment system 1 was used togenerate plasma from the process gas which was a gas mixture of ahydrogen fluoride gas component and argon gas component, and etch thesilicon oxide film. In a thirteenth experiment, the plasma treatmentsystem 1 was used to generate plasma from the process gas which was agas mixture of a hydrogen fluoride gas component, argon gas component,and PF₃ gas component, and etch the silicon oxide film. In the twelfthexperiment and the thirteenth experiment, the temperature of theelectrostatic chuck 20 was changed during etching of the silicon oxidefilm. In the twelfth experiment and the thirteenth experiment, theamount of hydrogen fluoride (HF) component and the amount of SiF3 in agas component phase during etching of the silicon oxide film weremeasured using a quadrupole mass spectrometer. FIGS. 18A and 18Billustrate the result of the twelfth experiment and the result of thethirteenth experiment. FIG. 18A illustrates the relation between thetemperature of the electrostatic chuck 20 during etching of the siliconoxide film and each of the amount of hydrogen fluoride (HF) componentand the amount of SiF₃ in the twelfth experiment. FIG. 18B illustratesthe relation between the temperature of the electrostatic chuck 20during etching of the silicon oxide film and each of the amount ofhydrogen fluoride (HF) component and the amount of SiF₃ in thethirteenth experiment.

As illustrated in FIG. 18A, in the twelfth experiment, when thetemperature of the electrostatic chuck 20 was approximately −60° C. orless, the amount of the etchant, that is, hydrogen fluoride (HF)component decreased, and the amount of SiF₃, which is a reaction productgenerated by etching of the silicon oxide film, increased. In otherwords, in the twelfth experiment, when the temperature of theelectrostatic chuck 20 was approximately −60° C. or less, the amount ofetchant used in the etching of the silicon oxide film increased. On theother hand, as illustrated in FIG. 18B, in the thirteenth experiment,when the temperature of the electrostatic chuck 20 was 20° C. or less,the amount of hydrogen fluoride (HF) component decreased and the amountof

SiF3 increased. In other words, in the thirteenth experiment, when thetemperature of the electrostatic chuck 20 was approximately 20° C. orless, the amount of etchant used in the etching of the silicon oxidefilm increased. The process gas used in the thirteenth experimentdiffers from the process gas used in the twelfth experiment in that itincludes PF₃ gas. In the thirteenth experiment, therefore, a phosphorouschemical species was present on the surface of the silicon oxide filmduring etching of the silicon oxide film. It can be understood that inthe presence of the phosphorous chemical species on the surface of thesilicon oxide film, adsorption of the etchant to the silicon oxide filmwas promoted although the temperature of the electrostatic chuck 20 wasrelatively as high as 20° C. or less. This has demonstrated that in thepresence of the phosphorous chemical species on the surface of thesubstrate, supply of the etchant to the bottom of the hole (recess) ispromoted and the etching rate of the silicon-containing film is therebyenhanced.

Fourteenth to sixteenth experiments for evaluation of the method MT andthe method MT2 will now be described. In the fourteenth to sixteenthexperiments, plasms of different process gases were generated using theplasma treatment system 1. The process gas used in the fourteenthexperiment included a hydrogen gas component, a fluorine gas component,a halogen gas component containing a halogen component other thanfluorine component, a hydrofluorocarbon gas component, a fluorocarbongas component, and a hydrocarbon gas component. The process gas used inthe fifteenth experiment included a hydrofluorocarbon gas component, afluorine gas component, and a halogen gas component containing a halogencomponent other than fluorine component. The process gas used in thesixteenth experiment contained a hydrogen fluoride gas component and afluorocarbon gas component. In each of the fourteenth to sixteenthexperiments, the amount of chemical species in a gas phase in thechamber 10 was measured using a quadrupole mass spectrometer. Theresults of the fourteenth to sixteenth experiments showed that thelargest amount of chemical species among the measured chemical specieswas hydrogen fluoride. Specifically, the amounts of hydrogen fluoridemeasured in the fourteenth to sixteenth experiments were 35.5%, 45.5%,and 66.7%, respectively. This has demonstrated that the amount ofhydrogen fluoride in plasma is largest when the process gas includeshydrogen fluoride gas component.

Regardless of the various exemplary embodiments that have beendescribed, any addition, elimination, replacement, and modification onthese embodiments may be allowable. The components in differentembodiments can be combined to form other embodiments.

For example, the plasma treatment system used in each of the method MTand the method MT2 may be a capacitively coupled plasma treatment systemother than the plasma treatment system 1. Alternatively, the plasmatreatment system used in each of the method MT and the method MT2 may bean inductively coupled plasma treatment system, an electron cyclotronresonance (ECR) plasma treatment system, or a plasma treatment systemthat generates plasma by using surface wave, for example, microwaves.

The plasma treatment system may also include another bias power sourcethat applies pulses of DC voltage with negative polarity intermittentlyor periodically to the bottom electrode 18, in addition to the biaspower source 64 that supplies the radio-frequency frequency power LF tothe bottom electrode 18.

FIG. 19 is a diagram of processing circuitry for performingcomputer-based operations described herein, especially with regard tocontrollers 41 and 80. FIG. 19 illustrates control circuitry 130 thatmay be used to control any computer-based control processes, such asprocess recipes, descriptions or blocks in flowcharts can be understoodas representing modules, segments or portions of code which include oneor more executable instructions for implementing specific logicalfunctions or steps in the process, and alternate implementations areincluded within the scope of the exemplary embodiments of the presentadvancements in which functions can be executed out of order from thatshown or discussed, including substantially concurrently or in reverseorder, depending upon the functionality involved, as would be understoodby those skilled in the art. The various elements, features, andprocesses described herein may be used independently of one another ormay be combined in various ways. All possible combinations andsub-combinations are intended to fall within the scope of thisdisclosure.

In FIG. 19, the processing circuitry 130 includes a CPU 1200 whichperforms one or more of the control processes described above/below. Theprocess data and instructions may be stored in memory 1202. Theseprocesses and instructions may also be stored on a storage medium disk1204 such as a hard drive (HDD) or portable storage medium or may bestored remotely. Further, the claimed advancements are not limited bythe form of the computer-readable media on which the instructions of theprocesses in this disclosure are stored. For example, the instructionsmay be stored on CDs, DVDs, in FLASH memory, RAM, ROM, PROM, EPROM,EEPROM, hard disk or any other information processing device with whichthe processing circuitry 130 communicates, such as a server or computer.

Further, the claimed advancements may be provided as a utilityapplication, background daemon, or component of an operating system, orcombination thereof, executing in conjunction with CPU 1200 and anoperating system such as Microsoft Windows, UNIX, Solaris, LINUX, AppleMAC-OS and other systems known to those skilled in the art.

The hardware elements in order to achieve the processing circuitry 130may be realized by various circuitry elements. Further, each of thefunctions of the above-described described embodiments may beimplemented by circuitry, which includes one or more processingcircuits. A processing circuit includes a particularly programmedprocessor, for example, processor (CPU) 1200, as shown in FIG. 19. Aprocessing circuit also includes devices such as an application specificintegrated circuit (ASIC) and conventional circuit components arrangedto perform the recited functions. In FIG. 19, the processing circuitry130 includes a CPU 1200 which performs the processes described above.The processing circuitry 130 may be a general-purpose computer or aparticular, special-purpose machine. In one embodiment, the processingcircuitry 130 becomes a particular, special-purpose machine when theprocessor 1200 is programmed to perform ESC in-situ replacement bycontrolling voltages and robot arms to replace the ESC without exposingthe reaction chamber to an external atmosphere.

Alternatively, or additionally, the CPU 1200 may be implemented on anFPGA, ASIC, PLD or using discrete logic circuits, as one of ordinaryskill in the art would recognize. Further, CPU 1200 may be implementedas multiple processors cooperatively working in parallel to perform theinstructions of the processes described above.

The processing circuitry 130 in FIG. 19 also includes a networkcontroller 1206, such as an Intel Ethernet PRO network interface cardfrom Intel Corporation of

America, for interfacing with network 1228. As can be appreciated, thenetwork 1228 can be a public network, such as the Internet, or a privatenetwork such as an LAN or WAN network, or any combination thereof andcan also include PSTN or ISDN sub-networks. The network 1228 can also bewired, such as an Ethernet network, or can be wireless such as acellular network including EDGE, 3G and 4G wireless cellular systems.The wireless network can also be Wi-Fi, Bluetooth, or any other wirelessform of communication that is known.

The processing circuitry 130 further includes a display controller 1208,such as a graphics card or graphics adaptor for interfacing with display1210, such as a monitor. A general purpose I/O interface 1212 interfaceswith a keyboard and/or mouse 1214 as well as a touch screen panel 1216on or separate from display 1210. General purpose I/O interface alsoconnects to a variety of peripherals 1218 including printers andscanners.

The general-purpose storage controller 1224 connects the storage mediumdisk 1204 with communication bus 1226, which may be an ISA, EISA, VESA,PCI, or similar, for interconnecting all of the components of theprocessing circuitry 130. A description of the general features andfunctionality of the display 1210, keyboard and/or mouse 1214, as wellas the display controller 1208, storage controller 1224, networkcontroller 1206, sound controller 1220, and general purpose I/Ointerface 1212 is omitted herein for brevity as these features areknown.

The exemplary circuit elements described in the context of the presentdisclosure may be replaced with other elements and structureddifferently than the examples provided herein. Moreover, circuitryconfigured to perform features described herein may be implemented inmultiple circuit units (e.g., chips), or the features may be combined incircuitry on a single chipset.

The functions and features described herein may also be executed byvarious distributed components of a system. For example, one or moreprocessors may execute these system functions, wherein the processorsare distributed across multiple components communicating in a network.The distributed components may include one or more client and servermachines, which may share processing, in addition to various humaninterface and communication devices (e.g., display monitors, smartphones, tablets, personal digital assistants (PDAs)). The network may bea private network, such as a LAN or WAN, or may be a public network,such as the Internet. Input to the system may be received via directuser input and received remotely either in real-time or as a batchprocess. Additionally, some implementations may be performed on modulesor hardware not identical to those described. Accordingly, otherimplementations are within the scope that may be claimed.

The disclosed embodiments further include the following modes (A1) to(A17), (B1) to (B92), and (C1) to (C19).

(A1). A method of etching comprising:

-   -   A) providing a substrate including a silicon-containing film in        a chamber of a plasma treatment system; and    -   B) etching the silicon-containing film with a chemical species        in plasma generated from a process gas in the chamber, the        process gas containing a halogen component and a phosphorus        component.

(A2). The method of (A1) further comprising C) forming a protective filmon a side wall of a recess formed during Step B, wherein

-   -   the protective film contains the phosphorous component contained        in the process gas.

(A3). The method of (A2), wherein Steps B and C are carried out at thesame time.

(A4). The method of any one of (Al) to (A3), wherein the process gascomprises at least one phosphorus compound selected from a groupconsisting of PF₃, PCl₃, PF₅, PCl₅, POCl₃, PH₃, PBr₃, and PBr₅ as amolecule containing the phosphorous component.

(A5). The method of any one of (A1) to (A4), wherein the process gasfurther contains a carbon component and a hydrogen component.

(A6). The method of (A5), wherein the process gas comprises at least onecomponent selected from a group consisting of H₂, HF, C_(x)H_(y),CH_(x)F_(y), and NH₃, as a molecule containing the hydrogen component,where x and y are each natural number.

(A7). The method of any one of (A1) to (A6), wherein the halogencomponent is a fluorine component.

(A8). The method of any one of (A1) to (A7), wherein the process gasfurther comprises an oxygen component.

(A9). The method of any one of (A1) to (A8), wherein thesilicon-containing film is a dielectric silicon-containing film.

(A10). The method of any one of (A1) to (A9), wherein thesilicon-containing film comprises at least one film selected from agroup consisting of a silicon oxide film, a silicon nitride film, and asilicon film.

(A11). The method of any one of (A1) to (A8), wherein thesilicon-containing film comprises at least two differentsilicon-containing sublayers.

(A12). The method of (A11), wherein the at least two silicon-containingsublayers comprise a silicon oxide sublayer and a silicon nitridesublayer.

(A13). The method of (A11), wherein the at least two silicon-containingsublayers comprise a silicon oxide sublayer and a silicon sublayer.

(A14). The method of (A11), wherein the at least two silicon-containingsublayers comprise a silicon oxide sublayer, a silicon nitride sublayer,and a silicon sublayer.

(A15). The method of any one of (A1) to (A14), wherein the substratefurther comprises a mask on the silicon-containing film.

(A16). The method of any one of (A1) to (A15), wherein the temperatureof the substrate is set to 0° C. or less at the start of Step B.

(A17). A plasma treatment system comprising:

-   -   a chamber;    -   a substrate support configured to support a substrate in the        chamber;    -   a gas supply unit configured to supply a process gas for etching        a silicon-containing film into the chamber, the process gas        containing a halogen component and a phosphorous component; and    -   a radio-frequency power source configured to generate        radio-frequency power for generating plasma from the process gas        in the chamber.

(B1). A method of etching comprising:

-   -   A) providing a substrate including a silicon-containing film in        a chamber of a plasma treatment system; and    -   B) etching the silicon-containing film with a chemical species        generated from a process gas plasma in the chamber, the process        gas containing a halogen component and a phosphorus component,        wherein    -   the process gas contains a first phosphorus-free gas at a first        flow rate and a second phosphorus gas component at a second flow        rate; and    -   the ratio of the second flow rate of the second gas to the first        flow rate of the first gas is above 0 and 0.5 or less.

(B2). The method of (B1), wherein the ratio is 0.075 or more and 0.3 orless.

(B3). The method of (B1), wherein the ratio is 0.1 or more and 0.25 orless.

(B4). The method of any one of (B1) to (B3), wherein the process gascomprises PF₃ as a molecule containing the phosphorous component.

(B5). The method of any one of (B1) to (B3), wherein the process gascomprises at least one phosphorus compound selected from a groupconsisting of PF₃, PCl₃, PF₅, PCl₅, POCl₃, PH₃, PBr₃, and PBr₅ as amolecule containing the phosphorous component.

(B6). The method of any one of (B1) to (B5), wherein the process gasfurther comprises a carbon component and a hydrogen component.

(B7). The method of (B6), wherein the process gas comprises at least onecomponent selected from a group consisting of H₂, HF, C_(x)H_(y),CH_(x)F_(y), and NH₃ as a molecule containing the hydrogen component,where x and y are each natural number.

(B8). The method of any one of (B1) to (B7), wherein the halogencomponent is a fluorine component.

(B9). The method of any one of (B1) to (B8), wherein the process gascomprises a fluorocarbon component as a molecule containing the halogencomponent.

(B10). The method of any one of (B1) to (B9), wherein the process gasfurther comprises an oxygen component.

(B11). The method of any one of (B1) to (B9), wherein the process gas isfree of oxygen component.

(B12). The method of any one of (B1) to (B11), wherein a protective filmis formed on a side wall of a recess formed during Step B.

(B13). The method of (B12), wherein the protective film containsphosphorus-oxygen bonds.

(B14). The method of (B13), wherein the protective film further containsphosphorus-silicon bonds.

(B15). The method of any one of (B1) to (B14), wherein the temperatureof the substrate is set to 0° C. or less at the start of Step B.

(B16). The method of any one of (B1) to (B15), wherein a radio-frequencybias power of 2 kW or more is supplied to a lower electrode in asubstrate support supporting the substrate in Step B.

(B17). The method of (B16), wherein the radio-frequency bias power is 10kW or more.

(B18). A method of etching comprising:

-   -   A) providing a substrate comprising a silicon-containing film in        a chamber of a plasma treatment system;    -   B) etching the silicon-containing film by a chemical species        generated from a process gas containing a halogen component and        a phosphorus component in the chamber to form a recess in the        silicon-containing film; and    -   C) forming a protective film containing phosphorus-oxygen bonds        derived from the phosphorus component contained in the process        gas on a side wall of the recess.

(B19). The method of (B18), wherein Steps B and C are carried out at thesame time.

(B20). The method of (B18), wherein Steps B and C are carried outindependently.

(B21). The method of any one of (B18) to (B20), wherein the protectivefilm has a thickness that decreases with the depth of the recess.

(B22). The method of any one of (B18) to (B21), wherein pulsed biaselectric power are applied to a bottom electrode in a substrate supportthat supports the substrate for performing Steps B and C; and

-   -   the bias electric power is radio-frequency bias power or pulsed        DC voltage with negative polarity.

(B23). The method of (B22), wherein the radio-frequency bias powersupplied to the bottom electrode in Step B is 2 kW or more.

(B24). The method of (B23), wherein the radio-frequency bias power is 10kW or more.

(B25). The method of any one of (B18) to (B24), wherein the plasma isgenerated by pulsed radio-frequency power.

(B26). The method of any one of (B18) to (B25), wherein the process gascomprises a first phosphorus-free gas component and a second phosphorusgas component.

(B27). The method of (B26), wherein the first gas and the second gas arealternately supplied to the chamber.

(B28). The method of (B26), wherein the ratio of the flow rate of thesecond gas to the flow rate of the first gas is above 0 and 0.5 or less.

(B29). The method of (B28), wherein the ratio is in the range from 0.075to 0.3.

(B30). The method of (B28), wherein the ratio is in the range from 0.1to 0.25.

(B31). The method of any one of (B18) to (B30), wherein the protectivefilm further comprises phosphorous-silicon bonds.

(B32). The method of any one of (B18) to (B31), wherein the process gascomprises PF₃ as a molecule containing the phosphorous component.

(B33). The method of any one of (B18) to (B31), wherein the process gascomprises at least one phosphorus compound selected from a groupconsisting PF₃, PCl₃, PF₅, PCl₅, POCl₃, PH₃, PBr₃, and PBr₅ as amolecule containing the phosphorous component.

(B34). The method of any one of (B18) to (B33), wherein the process gasfurther comprises a carbon component and a hydrogen component.

(B35). The method of (B34), wherein the process gas comprises at leastone component selected from a group consisting of H₂, HF, C_(x)H_(y),CH_(x)F_(y), and NH₃ as a molecule containing the hydrogen component,where x and y are each natural number.

(B36). The method of any one of (B18) to (B35), wherein the halogencomponent is a fluorine component.

(B37). The method of any one of (B18) to (B36), wherein the processcomprises a fluorocarbon component as a molecule containing the halogencomponent.

(B38). The method of any one of (B18) to (B37), wherein the oxygen issupplied from the silicon-containing film.

(B39). The method of (B38), wherein the process gas is free of oxygen.

(B40). The method of any one of (B18) to (B37), wherein the process gasfurther comprises an oxygen component.

(B41). The method of any one of (B18) to (B40), wherein the temperatureof the substrate is set to 0° C. or less at the start of Step B.

(B42). A method of etching comprising:

-   -   A) providing a substrate comprising a silicon-containing film in        a chamber of a plasma treatment system;    -   B) generating plasma from a process gas containing a halogen        component and a phosphorus component in the chamber; and    -   C) applying pulsed bias electric power to a bottom electrode of        a substrate support supporting the substrate in the presence of        the plasma in the chamber,    -   wherein the bias electric power is radio-frequency bias power or        pulsed DC voltage with negative polarity.

(B43). The method of (B42), wherein supply of the bias electric power tobe applied to the bottom electrode is alternately switched betweencontinuation and cessation, thereby applying the pulsed bias electricpower to the bottom electrode.

(B44). The method of (B42), wherein the level of the bias electric poweris varied to apply the pulsed bias electric power to the bottomelectrode.

(B45). The method of any one of (B42) to (B44), wherein

-   -   the pulsed bias electric power is periodically applied to the        bottom electrode,    -   each period of the pulsed bias electric power comprises a first        term and a second term, the level of the pulsed bias electric        power at the first term being higher than the level of the        pulsed bias electric power at the second term, and    -   the duty of the first term in the period is in the range from 1%        to 80%.

(B46). The method of (B45), wherein the frequency defining the period isin the range from 5 Hz to 100 kHz.

(B47). The method of (B45) or (B46), wherein the level of the electricpower at the first term is 2 kW or more.

(B48). The method of (B47), wherein the level of the electric power atthe first term is 10 kW or more.

(B49). The method of any one of (B42) to (B48), wherein the process gascomprises a first phosphorus-free gas component and a second phosphorusgas component.

(B50). The method of (B49), wherein the first gas and the second gas arealternately supplied to the chamber.

(B51). The method of (B50), wherein the term during which the first gasis supplied at least partially overlaps with the term during which thebias electric power is applied to the bottom electrode.

(B52). The method of (B49), wherein the ratio of the flow rate of thesecond gas to the flow rate of the first gas is above 0 and 0.5 or less.

(B53). The method of (B52), wherein the ratio is in the range from 0.075to 0.3.

(B54). The method of (B52), wherein the ratio is in the range from 0.1to 0.25.

(B55). The method of any one of (B42) to (B54), wherein Step Ccomprises:

-   -   C1) etching the silicon-containing film to form a recess; and    -   C2) forming a protective film on the side face of the recess,        wherein    -   Substep C1 and Substep C2 are carried out independently from        each other.

(B56). The method of (B55), wherein the protective film containsphosphorus-oxygen bonds.

(B57). The method of (B56), wherein the protective film further containsphosphorus-silicon bonds.

(B58). The method of any one of (B42) to (B57), wherein the process gascomprises PF₃ as a molecule containing the phosphorus component.

(B59). The method of any one of (B42) to (B57), wherein the process gascomprises at least one phosphorus compound selected from a groupconsisting PF₃, PCl₃, PF₅, PCl₅, POCl₃, PH₃, PBr₃, and PBr₅ as amolecule containing the phosphorus component.

(B60). The method of any one of (B42) to (B59), wherein the process gasfurther comprises a carbon component and a hydrogen component.

(B61). The method of (B60), wherein the process gas comprises at leastone component selected from a group consisting of H₂, HF, C_(x)H_(y),CH_(x)F_(y), C_(x)H_(y)F_(z), and NH₃ as a molecule containing thehydrogen component, where x, y, and z are each natural number.

(B62). The method of any one of (B42) to (B61), wherein the halogencomponent is a fluorine component.

(B63). The method of any one of (B42) to (B62), wherein the process gascomprises a fluorocarbon as a molecule containing the halogen component.

(B64). The method of any one of (B42) to (B63), wherein the process gasfurther comprises an oxygen component.

(B65). The method of any one of (B42) to (B63), wherein the process gasis free of oxygen.

(B66). The method of any one of (B42) to (B65), wherein the temperatureof the substrate is set to 0° C. or less at the start of Step B.

(B67). A method of etching comprising:

-   -   A) providing a substrate comprising at least two different        silicon-containing films in a chamber of a plasma treatment        system;    -   B) adjusting the substrate to a temperature of 0° C. or less;        and    -   C) etching the silicon-containing films by a chemical species        generated from a process gas containing PF₃ in the chamber.

(B68). The method of (B67), wherein the silicon-containing films aresilicon oxide films.

(B69). The method of (B67) or (B68), wherein the process gas comprises afirst phosphorus-free gas component and a second PF₃-containing gascomponent.

(B70). The method of (B69), wherein the ratio of the flow rate of thesecond gas to the flow rate of the first gas is above 0 and 0.5 or less.

(B71). The method of (B70), wherein the ratio is in the range from 0.075to 0.3.

(B72). The method of (B70), wherein the ratio is in the range from 0.1to 0.25.

(B73). The method of any one of (B67) to (B72), wherein the process gasfurther comprises a fluorocarbon.

(B74). The method of any one of (B67) to (B73), wherein the process gasfurther comprises a carbon component and a hydrogen component.

(B75). The method of (B74), wherein the process gas comprises at leastone component selected from a group consisting of H₂, HF, C_(x)H_(y),CH_(x)F_(y), and NH₃ as a molecule containing the hydrogen component,where x and y are each natural number.

(B76). The method of any one of (B67) to (B75), wherein the process gasfurther comprises an oxygen component.

(B77). The method of any one of (B67) to (B75), wherein the process gasis free of oxygen.

(B78). The method of any one of (B67) to (B77), wherein Step C involvesforming a recess and then forming a protective film on the side face ofthe recess.

(B79). The method of any one of (B67) to (B77), wherein Step Ccomprises:

-   -   C1) etching the silicon-containing films to form a recess; and    -   C2) forming a protective film on the side face of the recess,        wherein    -   Substep C1 and Substep C2 are carried out independently from        each other.

(B80). The method of (B78) or (B79), wherein the protective filmcontains phosphorus-oxygen bonds.

(B81). The method of (B80), wherein the protective film further containsphosphorus-silicon bonds.

(B82). The method of any one of (B67) to (B81), wherein Step C involvessupplying a radio-frequency bias electric power of 2 kW or more to abottom electrode in a substrate support supporting the substrate.

(B83). The method of (B82), wherein the electric power is 10 kW or more.

(B84). The method of any one of (B67) to (B83), wherein Step C involvesapplying a pulsed DC voltage with negative polarity to the bottomelectrode in the substrate support supporting the substrate.

(B85). The method of any one of (B1) or (B84), wherein thesilicon-containing film is a dielectric silicon-containing film.

(B86). The method of any one of (B1) to (B85), wherein thesilicon-containing film comprises at least one film selected from agroup consisting of a silicon oxide film, a silicon nitride film, and asilicon film.

(B87). The method of any one of (B1) to (B84), wherein thesilicon-containing film comprises at least two differentsilicon-containing sublayers.

(B88). The method of (B87), wherein the at least two silicon-containingsublayers comprise a silicon oxide sublayer and a silicon nitridesublayer.

(B89). The method of (B87), wherein the at least two silicon-containingsublayers comprise silicon oxide sublayers and silicon nitride sublayersthat are alternately disposed.

(B90). The method of (B87), wherein the at least two silicon-containingsublayers comprise a silicon oxide sublayer and an elemental siliconsublayer.

(B91). The method of (B87), wherein the at least two silicon-containingsublayers comprise silicon oxide sublayers and polysilicon sublayersthat are alternately stacked.

(B92). The method of any one of (B1) to (B91), wherein the substratefurther comprises a mask on the silicon-containing film.

(C1). A method of etching comprising:

-   -   A) providing a substrate comprising a silicon-containing film        and a mask in a chamber of a plasma treatment system; and    -   B) generating plasma from a process gas in the chamber to etch        the silicon-containing film, the process gas including a        hydrogen fluoride gas component, a phosphorus gas component, and        a carbon gas component.

(C2). The method of (C1), wherein among the flow rate of the hydrogenfluoride gas component, the flow rate of the phosphorus gas component,and the flow rate of the carbon gas component, the flow rate of thehydrogen fluoride gas component is largest.

(C3). The method of (C1), wherein

-   -   the process gas further includes a rare gas, and    -   among the flow rates of all the gases excluding the rare gas in        the process gas, the flow rate of the hydrogen fluoride gas        component is largest.

(C4). The method of any one of (C1) to (C3), wherein the temperature ofa substrate support that supports the substrate is set to a temperatureof 0° C. or less.

(C5). The method of (C4), wherein in Step (b), the temperature of asubstrate support that supports the substrate is set to a temperature of-40° C. or less.

(C6). The method of any one of (C1) to (C5), wherein the phosphorous gascomponent contains a halogen component.

(C7). The method of (C6), wherein the halogen component is a halogencomponent other than fluorine component.

(C8). The method of any one of (C1) to (C7), wherein the proportion ofthe flow rate of the phosphorus gas component in the sum of the flowrate of the hydrogen fluoride gas component, the flow rate of thephosphorus gas component, and the flow rate of the carbon gas componentis 2% or more.

(C9). The method of any one of (C1) to (C8), wherein the process gasfurther includes a fluorine-free halogen gas component.

(C10). The method of (C9), wherein the proportion of the flow rate ofthe halogen gas component in the sum of the flow rate of the hydrogenfluoride gas component, the flow rate of the phosphorus gas component,the flow rate of the carbon gas component, and the flow rate of thehalogen gas component is above 0% and 10% or less.

(C11). The method of any one of (C1) to (C10), wherein thesilicon-containing film comprises a silicon oxide film.

(C12). The method of (C11), wherein the silicon-containing film furthercomprises a silicon nitride film.

(C13). A process gas for plasma etching of a silicon oxide film, theprocess gas comprising a hydrogen fluoride gas component, a phosphorusgas component, and a carbon gas component.

(C14). The process gas of (C13), wherein among the flow rate of thehydrogen fluoride gas component, the flow rate of the phosphorus gascomponent, and the flow rate of the carbon gas component, the flow rateof the hydrogen fluoride gas component is largest.

(C15). The process gas of (C13), wherein the process gas furthercomprises a rare gas, and among the flow rates of all the gasesexcluding the rare gas in the process gas, the flow rate of the hydrogenfluoride gas component is largest.

(C16). The process gas of any one of (C13) to (C15), wherein thephosphorous gas component contains a halogen component.

(C17). The process gas of (C16), wherein the halogen component is ahalogen component other than component.

(C18). The process gas of any one of (C13) to (C15), wherein theproportion of the flow rate of the phosphorus gas component in the sumof the flow rate of the hydrogen fluoride gas component, the flow rateof the phosphorus gas component, and the flow rate of the carbon gascomponent is 2% or more. (C19). A plasma treatment system comprising:

-   -   a chamber;    -   a substrate support in the chamber,    -   a gas supply unit configured to supply a process gas including a        hydrogen fluoride gas component, a phosphorus gas component, and        a carbon gas component into the chamber;    -   a plasma generator configured to generate plasma from the        process gas; and    -   a controller configured to control the gas supply unit to supply        the process gas into the chamber to etch a silicon-containing        film of a substrate supported by the substrate support, and to        control the plasma generator to generate plasma from the process        gas in the chamber.

(D1). A method of etching comprising:

-   -   A) providing a substrate comprising a silicon-containing film        and a mask in a chamber of a plasma treatment system; and    -   B) generating plasma from a process gas in the chamber to etch        the silicon-containing film, the process gas including a        hydrogen fluoride gas component and a phosphorus gas component.

(D2). The method of (D1), wherein among the flow rate of the hydrogenfluoride gas component and the flow rate of the phosphorus gascomponent, the flow rate of the hydrogen fluoride gas component islargest.

(D3). The method of (D1), wherein

-   -   the process gas further includes a rare gas, and among the flow        rates of all the gases excluding the rare gas in the process        gas, the flow rate of the hydrogen fluoride gas component is        largest.

(D4). The method of any one of (D1) to (D3), wherein the temperature ofa substrate support that supports the substrate is set to a temperatureof 0° C. or less.

(D5). The method of (D4), wherein in Step (b), the temperature of asubstrate support that supports the substrate is set to a temperature of−40° C. or less.

(D6). The method of any one of (D1) to (D5), wherein the phosphorous gascomponent contains a halogen component.

(D7). The method of (D6), wherein the halogen component is a halogencomponent other than fluorine component.

(D8). The method of any one of (D1) to (D7), wherein the proportion ofthe flow rate of the phosphorus gas component in the sum of the flowrate of the hydrogen fluoride gas component and the flow rate of thephosphorus gas component is 2% or more.

(D9). The method of any one of (D1) to (D8), wherein the process gasfurther includes a fluorine-free halogen gas component.

(D10). The method of (D9), wherein the proportion of the flow rate ofthe halogen gas component in the sum of the flow rate of the hydrogenfluoride gas component, the flow rate of the phosphorus gas component,and the flow rate of the halogen gas component is above 0% and 10% orless.

(D11). The method of any one of (D1) to (D10), wherein thesilicon-containing film comprises a silicon oxide film.

(D12). The method of (D11), wherein the silicon-containing film furthercomprises a silicon nitride film.

(D13). A process gas for plasma etching of a silicon oxide film, theprocess gas comprising a hydrogen fluoride gas component and aphosphorus gas component.

(D14). The process gas of (D13), wherein among the flow rate of thehydrogen fluoride gas component and the flow rate of the phosphorus gascomponent, the flow rate of the hydrogen fluoride gas component islargest.

(D15). The process gas of (D13), wherein the process gas furthercomprises a rare gas, and among the flow rates of all the gasesexcluding the rare gas in the process gas, the flow rate of the hydrogenfluoride gas component is largest.

(D16). The process gas of any one of (D13) to (D15), wherein thephosphorous gas component contains a halogen component.

(D17). The process gas of (D16), wherein the halogen component is ahalogen component other than component.

(D18). The process gas of any one of (D13) to (D15), wherein theproportion of the flow rate of the phosphorus gas component in the sumof the flow rate of the hydrogen fluoride gas component and the flowrate of the phosphorus gas component is 2% or more.

(D19). A plasma treatment system comprising:

-   -   a chamber;    -   a substrate support in the chamber,    -   a gas supply unit configured to supply a process gas including a        hydrogen fluoride gas component, and a phosphorus gas component        into the chamber;    -   a plasma generator configured to generate plasma from the        process gas; and    -   a controller configured to control the gas supply unit to supply        the process gas into the chamber to etch a silicon-containing        film of a substrate supported by the substrate support, and to        control the plasma generator to generate plasma from the process        gas in the chamber.

It should be understood that the embodiments described above areprovided for mere illustrative purposes and can be modified within thescope of the present disclosure. The embodiments disclosed herein shouldnot be construed to limit of the scope of the disclosure and the scopeof the disclosure should be determined based on the description of theattached claims.

1. A method of etching comprising: (a) providing a substrate including asilicon-containing film in a chamber of a plasma treatment system; and(b) etching the silicon-containing film with a chemical species inplasma generated from a process gas in the chamber, the process gasincluding a phosphorus gas component, a fluorine gas component, and ahydrogen gas component containing at least one component selected fromthe group consisting of hydrogen fluoride, H2, ammonia, andhydrocarbons.
 2. The method of claim 1, wherein the fluorine gascomponent includes at least one gas selected from the group consistingof a fluorocarbon gas and a carbon-free fluorine gas.
 3. The method ofclaim 2, wherein the process gas further includes a hydrofluorocarbongas.
 4. The method of claim 2, wherein the fluorocarbon gas includes atleast one fluorocarbon gas selected from the group consisting of CF₄,C₃F₈, C₄F₆, and C₄F₈.
 5. The method of claim 4, wherein the carbon-freefluorine gas is nitrogen trifluoride gas or sulfur hexafluoride gas. 6.The method of claim 1, wherein the process gas further includes ahalogen gas component containing a halogen component other than fluorinecomponent.
 7. A method of etching comprising: (a) providing a substrateincluding a silicon-containing film in a chamber of a plasma treatmentsystem; and (b) etching the silicon-containing film with a chemicalspecies in plasma generated from a process gas in the chamber, theprocess gas including a phosphorus gas component, a fluorine gascomponent, a hydrofluorocarbon gas component, and a halogen gascomponent containing a halogen component other than fluorine component.8. The method of claim 7, wherein the fluorine gas component includes atleast one gas selected from the group consisting of a fluorocarbon gasand a carbon-free fluorine gas.
 9. The method of claim 8, wherein thecarbon-free fluorine gas is nitrogen trifluoride gas or sulfurhexafluoride gas.
 10. The method of claim 6, wherein the halogen gascomponent is Cl₂ gas and/or HBr gas.
 11. The method of claim 1, whereinthe ratio of the flow rate of a second gas to the flow rate of a firstgas in the process gas is above 0 and 0.5 or less, the first gas is allgases included in the process gas excluding the phosphorus gascomponent, and the second gas is the phosphorus gas component.
 12. Themethod of claim 11, wherein the ratio is 0.075 or more and 0.3 or less.13. The method of claim 1, further comprising forming a protective filmcontaining phosphorous-oxygen bonds contained in the process gas on aside wall surface of a recess formed by the etching.
 14. The method ofclaim 1, wherein Step (b) includes periodically applying pulsed biaselectric power to a bottom electrode of a substrate support thatsupports the substrate, when the plasma is present in the chamber, andthe bias electric power is radio-frequency bias electric power or pulsedDC voltage with negative polarity.
 15. The method of claim 14, wherein afrequency defining a period in which the pulsed bias electric power isapplied to the bottom electrode is 5 Hz or higher and 100 kHz or lower.16. The method of claim 1, further comprising, before Step (b), settingthe temperature of a substrate support that supports the substrate to 0°C. or less.
 17. A method of etching comprising: (a) providing asubstrate having a silicon-containing film and a mask in a chamber of aplasma treatment system; and (b) generating plasma from a process gas inthe chamber to etch the silicon-containing film, the process gasincluding a hydrogen fluoride gas component, a phosphorus gas component,and a carbon gas component.
 18. The method of claim 17, wherein amongthe flow rate of the hydrogen fluoride gas component, the flow rate ofthe phosphorus gas component, and the flow rate of the carbon gascomponent, the flow rate of the hydrogen fluoride gas component islargest.
 19. The method of claim 17, wherein the process gas furtherincludes a rare gas, and among the flow rates of all gases in theprocess gas excluding the rare gas, the flow rate of the hydrogenfluoride gas component is largest.
 20. The method of claim 17, whereinin Step (b), the temperature of a substrate support that supports thesubstrate is set to a temperature of 0° C. or less or −40° C. or less.21. The method of claim 17, wherein the process gas further includes afluorine-free halogen gas component.
 22. The method of claim 17, whereinthe mask includes a carbon component.
 23. The method of claim 1, whereinthe silicon-containing film includes a silicon oxide film, a siliconoxide film and a silicon nitride film, or a silicon oxide film and apolycrystalline silicon film.
 24. The method of claim 1, wherein thephosphorus gas component includes a halogen component.
 25. The method ofclaim 1, wherein the phosphorus gas component includes the phosphorouscomponent selected from the group consisting of PF₃, PCl₃, PF₅, PCl₅,POCl₃, PH₃, PBr₃, and PBr₅.
 26. The method of claim 1, wherein thephosphorus gas component includes a fluorine component.
 27. The methodof claim 26, wherein the phosphorus gas component includes PF₃ or PF₅.28. The method of claim 17, wherein the carbon gas component includes atleast one gas selected from the group consisting of a fluorocarbon gasand a hydrofluorocarbon gas.
 29. The method of claim 28, wherein thecarbon gas component includes at least two carbon atoms.
 30. The methodof claim 1, wherein the process gas further includes an oxygen gascomponent.
 31. The method of claim 18, wherein the proportion of theflow rate of the hydrogen fluoride gas component to the flow rate of theprocess gas excluding a rare gas is 50% or more and less than 99%. 32.The method of claim 17, wherein the proportion of the flow rate of thephosphorous gas component to the flow rate of the process gas excludinga rare gas is 1% or more and 20% or less.
 33. The method of claim 1,wherein the plasma treatment system is a capacitively coupled plasmatreatment system.
 34. The method of claim 33, wherein in Step (b), theplasma is generated by supplying a radio-frequency power to a bottomelectrode of a substrate support configured to support the substrate inthe chamber.
 35. The method of claim 33, wherein the plasma treatmentsystem includes a substrate support in the chamber and an upperelectrode disposed above the substrate support, and in Step (b), theplasma is generated by supplying a radio-frequency power to the upperelectrode.
 36. The method of claim 34, wherein a frequency of theradio-frequency power is a frequency within a frequency range from 27MHz to 100 MHz.
 37. The method of claim 1, wherein the plasma treatmentsystem is an inductively coupled plasma treatment system.
 38. A plasmatreatment system for etching a mask of a substrate having asilicon-containing film and the mask comprising: a chamber; a substratesupport configured to support the substrate in the chamber; a gas supplyunit configured to supply a process gas containing a hydrogen fluoridegas component, a phosphorus gas component, and a carbon gas component inthe chamber; a plasma generator configured to generate plasma from theprocess gas; and a controller configured to control the gas supply unitto supply the process gas into the chamber to etch thesilicon-containing film of the substrate supported by the substratesupport, and to control the plasma generator to generate plasma from theprocess gas in the chamber.